From 9f14b5e076b5cf3310445f6222b7be4d6e2cc94f Mon Sep 17 00:00:00 2001
From: Bruno Raoult <braoult@gmail.com>
Date: Thu, 21 Jan 2021 19:09:41 +0100
Subject: [PATCH] started migration stack->tree

---
 Makefile |   6 +-
 best.c   | 100 ++++++++++++++++++++++++++
 eval.c   |  95 ++++++++++++++----------
 lceb.c   |  76 +++++++++++++++-----
 lceb.h   | 103 ++++++++++++++++++++------
 oper.c   |  48 +++++++++++--
 stack.c  | 166 ++++++++++++++++++++++++------------------
 tree.c   | 214 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 8 files changed, 649 insertions(+), 159 deletions(-)
 create mode 100644 best.c

diff --git a/Makefile b/Makefile
index e8895fb..72b7521 100644
--- a/Makefile
+++ b/Makefile
@@ -4,11 +4,11 @@ CFLAGS := -w -g -pg -DDEBUG
 TIME := \time -f "\ttime: %E real, %U user, %S sys\n\tcontext-switch:\t%c+%w, page-faults: %F+%R\n"
 export PATH := .:$(PATH)
 
-TARGETS=lceb tree oper stack eval
+TARGETS=lceb tree oper stack eval best
 INCLUDES=lceb.h
 OBJS=$(TARGETS:=.o)
 
-.PHONY: all clean stack eval
+.PHONY: all clean stack eval best
 
 all: $(TARGETS)
 
@@ -19,6 +19,8 @@ tree: tree.c lceb.h
 oper: oper.c lceb.h
 	$(CC) $(CFLAGS) -DSTANDALONE -o $@ $?
 
+eval.o stack.o best.o: lceb.h
+
 ex2: ex2-c
 	@$(TIME) ex2-c < $(INPUT)
 
diff --git a/best.c b/best.c
new file mode 100644
index 0000000..b1f5d87
--- /dev/null
+++ b/best.c
@@ -0,0 +1,100 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <malloc.h>
+#include <values.h>
+#include "lceb.h"
+
+static int target=0;
+//static int best=MAXINT;
+static int bestdiff=MAXINT;
+static int bestops=MAXINT;
+
+static BEST bests[1024];        /* TODO: should be dynamic */
+static int nbests=0;
+
+#define DIFF(a, b) ((a)>(b)?(a)-(b):(b)-(a))
+
+void set_target(n)
+    int n;
+{
+    target=n;
+}
+
+int check_best(res, nops, node, values, ops)
+    int res;
+    int nops;
+    NODE *node;
+    int *values;
+    char *ops;
+{
+    int diff, found=0;
+
+    diff=DIFF(target, res);
+#   ifdef DEBUG
+    printf("check_best: res=%d diff=%d nops=%d\n", res, diff, nops);
+#   endif
+    if (diff < bestdiff || (diff == bestdiff && nops < bestops)) {
+#       ifdef DEBUG
+        printf("NEW BEST! res=%d diff=%d nops=%d\n", res, diff, nops);
+        printf("check_best: res=%d diff=%d nops=%d\n", res, diff, nops);
+#       endif
+        //best=res;
+        bestdiff=diff;
+        bestops=nops;
+        nbests=0;
+        found=1;
+        //return 1;
+    } else if (diff == bestdiff && nops == bestops) {
+#       ifdef DEBUG
+        printf("NEW BEST SOLUTION (%d):  res=%d diff=%d nops=%d\n", nbests+1, res, diff, nops);
+#       endif
+        found=1;
+    }
+    if (found) {
+        bests[nbests].res=res;
+        bests[nbests].diff=diff;
+        bests[nbests].oper=ops;
+        bests[nbests].root=node;
+        bests[nbests].values=values;
+        nbests++;
+        return 1;
+    }
+    return 0;
+}
+
+void print_best(node, values, pops, depth)
+    NODE *node;
+    int *values;
+    char *pops;
+    int depth;
+{
+    static int *vals;
+    static char *ops;
+
+    if (depth == 0) {
+        vals=values;
+        ops=pops;
+    }
+    if (node->type == TREE_LEAF) {
+        printf("%d ", *vals);
+        vals++;
+    } else {
+        print_best(node->left, vals, ops, depth+1);
+        print_best(node->right, vals, ops, depth+1);
+        printf(" %c ", *ops);
+        ops++;
+    }
+    if (depth == 0)
+        putchar('\n');
+}
+
+void print_bests()
+{
+    int i;
+    printf("BESTS: diff=%d solutions=%d nops=%d\n", bestdiff, nbests, bestops);
+    for (i=0; i<nbests; ++i) {
+        printf("res = %d : ", bests[i].res);
+        print_best(bests[i].root, bests[i].values, bests[i].oper, 0);
+    }
+}
diff --git a/eval.c b/eval.c
index 7dbb53f..58cf7e8 100644
--- a/eval.c
+++ b/eval.c
@@ -1,27 +1,52 @@
 #include <stdio.h>
 #include "lceb.h"
 
-int eval_cell(pos)
-    STACKELT *pos;
-{
-    STACKELT *prev=pos-1;
-    int curop=pos->curop, nop=pos->nop;
-    int val1, val2;
-    char op;
-    int res;
 
-    while (curop<nop) {
-        op=pos->op[curop];
-        val2=pos->val;
-        res=-1;
-        printf("eval_cell(%c, %d)\n", op, val2);
-        while ((val1=prev->val) == -1)
-            prev--;
+int eval_node(node, depth, pvals, pops)
+    NODE *node;
+    int depth;
+    int *pvals;
+    char *pops;
+{
+    static int *vals, *val_zero;
+    static char *ops, *ops_zero;
+    static int ncalc;
+    static *node_zero;
+    int val1, val2, op, res=-1, i;
+
+    if (depth == 0) {
+        val_zero=vals=pvals;
+        ops_zero=ops=pops;
+        node_zero=node;
+        ncalc=0;
+    }
+#   ifdef  DEBUG1
+    for (i=0; i<=depth; ++i)
+        printf("  ");
+    printf("eval : depth=%d : ", depth);
+    if (node->type == TREE_NODE) {
+        printf("node(%c)\n", *ops);
+    } else {
+        printf("val(%d)\n", *vals);
+    }
+#   endif
+    if (node->type == TREE_LEAF) {
+        node->val=*vals;
+        res=*vals;
+        vals++;
+    } else {
+        op=*ops;
+        node->op=*ops;
+        ops++;
+        ncalc++;
+        //printf("NEW node(%s)\n", ops);
+        val1=eval_node(node->left, depth+1, pvals, ops);
+        if (val1 <= 0)
+            return -1;
+        val2=eval_node(node->right, depth+1, pvals, ops);
+        if (val2 <= 0)
+            return -1;
         switch (op) {
-            case Nop:
-            case End:
-                return val2;
-                break;
             case Add:
                 res=val1+val2;
                 break;
@@ -36,27 +61,19 @@ int eval_cell(pos)
                 if (val1 > val2 && (val1 % val2 == 0))
                     res=val1/val2;
                 break;
+            case Nop:
+            case End:
+                fprintf(stderr, "Fatal: bad op [%d] in eval\n", op);
+                exit(1);
+                break;
         }
-        curop++;
-        if (res==-1)
-            break;
-        pos->val=res;
-        printf("\t--> eval=%d\n", res);
-    }
-    return res;
-}
-
-int eval_stack(stack)
-    STACK *stack;
-{
-    int pos, last=stack->last, res;
-    STACKELT *pstack=stack->stack;
-
-    printf("+++++ eval_stack: addr=%p\n", pstack);
-    for (pos=1; pos<last; ++pos) {
-        //printf("eval_stack(%d/%d): addr=%p\n", pos, stack->last, pstack+pos);
-        res=eval_cell(stack->stack+pos);
-        //printf("  -> val(%d)=%d\n", pos, res);
     }
+    if (res > 0)
+        check_best(res, ncalc, node_zero, val_zero, ops_zero);
+#   ifdef  DEBUG1
+    for (i=0; i<=depth; ++i)
+        printf("  ");
+    printf("res=%d\n", res);
+#   endif
     return res;
 }
diff --git a/lceb.c b/lceb.c
index a9bcd32..9156d7f 100644
--- a/lceb.c
+++ b/lceb.c
@@ -14,17 +14,20 @@
 #include <string.h>
 #include "lceb.h"
 
-
-
 int main(ac, av)
     int ac;
     char **av;
 {
     unsigned target;
     STACK *stack;
-    int i, stacksize, val, res;
-    char *ops="+-*/", *opscomb;
-    int len_ops=strlen(ops), ncombs, nops;
+    int i, j, k, stacksize, val, res;
+    //char *ops="+-*/", *opscomb;
+    //int len_ops=strlen(ops), ncombs, nops;
+    int ncombs, nstacks, ntrees, nops;
+    TREE *tree;
+    int intarray[1024];
+    int eval;
+    char *comb;
 
     if (ac < 4 || ac > 2+MAXINPUT) {
         fprintf(stderr, "usage: %s target n1 n2 [...n%d]\n", *av, MAXINPUT);
@@ -33,36 +36,73 @@ int main(ac, av)
     target=atoi(av[1]);
     stacksize=2*(ac-2)-1;
     nops=ac-2-1;
-    ncombs=ncombinations(len_ops, nops);
+
+    printf("A\n");
+    gen_combinations(nops);
+    printf("A\n");
+    //ncombs=ncombinations(len_ops, nops);
+    ncombs=n_combs();
+    printf("A\n");
+    print_combs();
     printf("target=%d\nstacksize=%d\nops_comb=%d\n", target, stacksize, ncombs);
-    printf("len_ops=%d\nnops=%d\nops_comb=%d\n", len_ops, nops, ncombs);
-    stack=new_stack(stacksize, "Main Stack");
+    set_target(target);
+    //printf("len_ops=%d\nnops=%d\nops_comb=%d\n", len_ops, nops, ncombs);
+    stack=new_stack(stacksize, "Main Stack", 1);
     for (i=2; i<ac; ++i) {
         val=atoi(av[i]);
-        push_stack(stack, Nop, val);
+        push_stack(stack, val);
     }
 
-    print_stack(stack, 1);
-    printf("sorting stack...\n");
-    mergesort_stack(stack->stack, 0, stack->last-1);
-    print_stack(stack, 1);
+    //print_stack(stack, 1);
+    gen_stacks(stack); // printf("sorting stack...\n");
+    print_stacks();
+    //mergesort_stack(stack->stack, 0, stack->last-1);
+    //print_stack(stack, 1);
 
-    i=1;
+    /*i=1;
     do {
         printf("permutation %2d: ", i++);
         print_stack(stack, 0);
     } while (permute_stack(stack->stack, stack->last));
+    */
 
-    printf("operators combinations (%d) = ", ncombs);
-    for (i=0; i<ncombs; ++i) {
-        opscomb=combination(ops, nops, i);
+    gen_tree(intarray, nops, 0, 0);
+    printf("operators combinations : %d\n", ncombs);
+
+    nstacks=n_stacks();
+    ntrees=n_trees();
+    printf("nstacks=%d\nncombs=%d\nntrees=%d\n", nstacks, ncombs, ntrees);
+    for (i=0; i<ntrees; ++i) {
+        tree=nth_tree(i);
+        for (j=0; j<ncombs; ++j) {
+            comb=nth_comb(j);
+            for (k=0; k<nstacks; ++k) {
+                stack=nth_stack(k);
+
+                eval=eval_node(tree->head, 0, stack->stack, comb);
+                if (eval > 0) {
+#ifdef DEBUG1
+                    printf("============================== %d, %d, %d\n", i, j, k);
+                    print_tree(tree, 0);
+                    print_comb(j);
+                    print_stack(stack, 0);
+                    printf("eval=%d\n", eval);
+#endif
+
+                }
+            }
+        }
+        //opscomb=combination(ops, nops, i);
         //printf("OPS=%s\n", opscomb);
+        //eval=eval_node(tree->head, 0, stack->stack, nth_comb(0));
+        //printf("eval=%d\n", eval);
+
         //set_ops_stack(stack, opscomb);
         //print_stack(stack, 0);
         //res=eval_stack(stack);
         //printf("EVAL=%d\n", res);
     }
     printf("\n");
-
+    print_bests();
     exit(0);
 }
diff --git a/lceb.h b/lceb.h
index 32d3b82..be51b75 100644
--- a/lceb.h
+++ b/lceb.h
@@ -7,46 +7,103 @@ typedef enum {
     Nop='N',
     Add='+',
     Sub='-',
-    Mul='x',
+    Mul='*',
     Div='/',
     End='\0'                                      /* Only for "printf" */
 } OPER;
 
-typedef struct stackelt {
-    int val;
-    int nop;                                      /* number of operators */
-    int curop;                                    /* current operator */
-    char op[MAXINPUT];                            /* MAXINPUT-1 + ending \0 */
-    int next, prev;                               /* for eval: avoids restructuring stack */
-} STACKELT;
-
 typedef struct stack {
     char name[80];
     int size;
     int last;
-    int eval;
-    STACKELT *stack;
+    struct stack *next;
+    int *stack;
 } STACK;
 
+#define TREE_UNDEF      (-1)    /* should not happen */
+#define TREE_LEAF       0
+#define TREE_NODE       1
+#define TREE_LEFT       'L'
+#define TREE_RIGHT      'R'
+#define TREE_TOP        'T'
+
+#define EMPTY           -1
+
+typedef struct node {
+    int type;                   /* TREE_LEAF or TREE_NODE */
+    int op;
+    int val;
+    int eval;
+    struct node *left;
+    struct node *right;
+    struct node *next;          /* for transversal walk and free nodes */
+} NODE;
+
+typedef struct tree {
+    char name[80];
+    NODE *head;
+    struct tree *next;
+    int nodes;                  /* number of nodes */
+    int leaves;                 /* number of leaves */
+    int depth;                  /* max depth */
+} TREE;
+
+typedef struct best {
+    int res;
+    int diff;
+    int nops;
+    char *oper;
+    NODE *root;
+    int *values;
+} BEST;
+
 /* tree.c */
+extern NODE *get_node();
+extern void free_node(NODE *node);
+extern void print_node(NODE *node, char side, int depth, int details);
+extern void print_tree(TREE *tree, int details);
+extern void print_trees(int details);
+extern TREE *new_tree(char *name);
+extern NODE *build_tree(int *desc, int size);
 extern void gen_tree(int *seq, int n, int nb1, int nb0);
+extern TREE *nth_tree(int n);
+extern int n_trees();
 
 /* stack.c */
 extern void print_stack(STACK *stack, int details);
-extern STACK *new_stack(int size, char *name);
-extern STACKELT *push_stack(STACK *stack, OPER op, int val);
-extern STACKELT *pop_stack(STACK *stack);
+extern void print_stacks();
+extern int keep_stack(STACK *stack);
+extern STACK *new_stack(int size, char *name, int keep);
+extern int *push_stack(STACK *stack, int val);
+extern int *pop_stack(STACK *stack);
 extern STACK *dup_stack(STACK *stack, char *name);
-extern void swap_stack(STACKELT *elts, int i, int j);
-extern int permute_stack(STACKELT *array, int n);
-extern void mergesort_stack(STACKELT *array, int left, int right);
-extern STACKELT *set_op_stack(STACK *stack, int pos, OPER op);
-extern STACKELT *set_ops_stack(STACK *stack, char *ops);
+extern void swap_stack(int *elts, int i, int j);
+extern int permute_stack(int *array, int n);
+extern int gen_stacks(STACK *stack);
+extern void mergesort_stack(int *array, int left, int right);
+extern STACK *nth_stack(int n);
+extern int n_stacks();
+// extern STACKELT *set_op_stack(STACK *stack, int pos, OPER op);
+// extern STACKELT *set_ops_stack(STACK *stack, char *ops);
 
 /* oper.c */
-extern unsigned ncombinations(int nops, int len);
-extern char *combination(char *ops, int len, int n);
+extern void print_comb(int n);
+extern void print_combs();
+//extern unsigned n_combine(int nops, int len);
+//extern char *combine(char *ops, int len, int n);
+extern void gen_combinations(int nops);
+extern int n_combs();
+extern char *nth_comb(int n);
 
 /* eval.c */
-extern int eval_cell(STACKELT *pos);
-extern int eval_stack(STACK *stack);
+/* stack version */
+//extern int eval_cell(STACKELT *pos);
+//extern int eval_stack(STACK *stack);
+/* tree version */
+extern int eval_node(NODE *node, int depth, int *pvals, char *pops);
+
+/* best.c */
+extern void set_garget (int n);
+extern int check_best(int res, int nops, NODE *node, int *values, char *ops);
+extern void print_best(NODE *node, int *values, char *pops, int depth);
+extern void print_bests();
diff --git a/oper.c b/oper.c
index 392d44e..748c5e7 100644
--- a/oper.c
+++ b/oper.c
@@ -2,7 +2,23 @@
 #include <malloc.h>
 #include "lceb.h"
 
-unsigned ncombinations(nops, len)
+static char *combs[1024]; /* should be dynamic */
+static int ncombs=0;
+
+void print_comb(n)
+    int n;
+{
+    printf("comb %d/%d=[%s]\n", n, ncombs, combs[n]);
+}
+void print_combs()
+{
+    int i;
+    printf("op combs: ");
+    for (i=0; i<ncombs; ++i)
+        printf("%s ", combs[i]);
+    putchar('\n');
+}
+static unsigned n_combine(nops, len)
     int nops, len;
 {
     int result = 1;
@@ -15,7 +31,7 @@ unsigned ncombinations(nops, len)
     return result;
 }
 
-char *combination(ops, len, n)
+static char *combine(ops, len, n)
     char *ops;                                    /* string to combine */
     int len;                                      /* len of result */
     int n;                                        /* iteration # */
@@ -35,6 +51,30 @@ char *combination(ops, len, n)
     return res;
 }
 
+void gen_combinations(nops)
+    int nops;
+{
+    char *ops="+-*/";
+    int i, n_combs;
+    int len_ops=strlen(ops);
+
+    n_combs=n_combine(len_ops, nops);
+    printf("gen: n=%d\n", n_combs);
+    for (i=0; i<n_combs; ++i) {
+        combs[ncombs]=strdup(combine(ops, nops, i));
+        ncombs++;
+    }
+}
+int n_combs()
+{
+    return ncombs;
+}
+char *nth_comb(n)
+    int n;
+{
+    return combs[n];
+}
+
 #ifdef STANDALONE
 int main(ac, av)
     int ac;
@@ -45,10 +85,10 @@ int main(ac, av)
     int i, j, nops, ncombs;
 
     nops=atoi(*(av+1));
-    ncombs=ncombinations(len_ops, nops);
+    ncombs=n_combine(len_ops, nops);
     printf("# operators combinations : %d\nlist = ", ncombs);
     for (i=0; i<ncombs; ++i) {
-        p=combination(ops, nops, i);
+        p=combine(ops, nops, i);
         printf("[%s]\n", p);
         //for (j=0; j<4; ++j)
         //    distribute(j, p);
diff --git a/stack.c b/stack.c
index 70b0349..2d939f1 100644
--- a/stack.c
+++ b/stack.c
@@ -3,6 +3,9 @@
 #include <string.h>
 #include "lceb.h"
 
+static STACK *stacks=NULL;
+static int nstacks=NULL;
+
 void print_stack(stack, details)
     STACK *stack;
     int details;
@@ -11,77 +14,97 @@ void print_stack(stack, details)
 
     if (details) {
         printf("Stack [%s] dump: %d/%d used\n", stack->name, stack->last, stack->size);
-        printf("\tValue: %4d\n", stack->eval);
+        //printf("\tValue: %4d\n", stack->eval);
         for (i=0; i<stack->last; ++i)
-            printf("\t%02d: Op=%s Val=%4d\n",
-                   i, (char *)stack->stack[i].op, stack->stack[i].val);
+            printf("\t%02d: Val=%4d\n",
+                   i, stack->stack[i]);
     } else {
         printf("Stack [%s] : ", stack->name);
         for (i=0; i<stack->last; ++i) {
-            printf("%d[%s] ", stack->stack[i].val, (char *)stack->stack[i].op);
+            printf("%d ", stack->stack[i]);
         }
         printf("\n");
     }
 }
 
-STACK *new_stack(size, name)
+print_stacks()
+{
+    STACK *stack=stacks;
+    printf("nstacks=%d\n", nstacks);
+    while (stack) {
+        print_stack(stack, 1);
+        stack=stack->next;
+    }
+}
+
+int keep_stack(stack)
+    STACK *stack;
+{
+    stack->next=stacks;
+    stacks=stack;
+    nstacks++;
+}
+
+STACK *new_stack(size, name, keep)
     int size;                                     /* 0 if empty */
     char *name;
+    int keep;
 {
     STACK *stack;
-    STACKELT *pelt;
+    int *pelt;
     int i;
 
     stack=malloc(sizeof (STACK));
     stack->stack=NULL;
     stack->size=0;
     stack->last=0;
-    stack->eval=0;
+    //stack->eval=0;
     strncpy(stack->name, name? name: "No name", sizeof(stack->name));
     if (size) {
-        pelt=malloc(size*sizeof(STACKELT));
+        pelt=malloc(size*sizeof(int));
         stack->size=size;
         stack->stack=pelt;
+        if (keep)
+            keep_stack(stack);
         for (i=0; i<size; ++i) {
-            (pelt+i)->nop=0;
-            (pelt+i)->curop=0;
-            (pelt+i)->op[0]=End;
-            (pelt+i)->val=-1;
-            (pelt+i)->next=i+1;
-            (pelt+i+1)->prev=i;
+            //(pelt+i)->nop=0;
+            //(pelt+i)->curop=0;
+            //(pelt+i)->op[0]=End;
+            pelt[i]=-1;
+            //(pelt+i)->next=i+1;
+            //(pelt+i+1)->prev=i;
         }
-        (pelt+i-1)->next=-1;
+        //(pelt+i-1)->next=-1;
     }
     return stack;
 }
 
-STACKELT *push_stack(stack, op, val)
+int *push_stack(stack, val)
     STACK *stack;
-    OPER op;
     int val;
 {
     int pos=stack->last;
     int size=stack->size;
-    STACKELT *pelt=stack->stack+stack->last;
+    int *pelt=stack->stack+stack->last;
 
     if (pos >= size) {
         fprintf(stderr, "stack overflow: size=%d last=%d\n", size, pos);
         return NULL;
     }
-    pelt->nop=0;
-    pelt->curop=0;
+    //pelt->nop=0;
+    //pelt->curop=0;
     //pelt->op[0]=op;
-    pelt->val=val;
+    *pelt=val;
     stack->last++;
     return pelt;
 }
 
-STACKELT *pop_stack(stack)
+int *pop_stack(stack)
     STACK *stack;
 {
     int pos=stack->last+1;
     int size=stack->size;
-    STACKELT *pelt=stack->stack+stack->last;
+    int *pelt=stack->stack+stack->last;
 
     if (pos==0) {
         fprintf(stderr, "stack empty: size=%d last=%d\n", size, pos);
@@ -96,40 +119,42 @@ STACK *dup_stack(stack, name)
     char *name;
 {
     STACK *new;
-    STACKELT *src=stack->stack, *dst;
+    int *src=stack->stack, *dst;
     int size=stack->size, last=stack->last, i;
 
-    new=new_stack(size, name);
+    new=new_stack(size, name, 0);
+    new->last=stack->last;
     dst=new->stack;
     for (i=0; i<last; ++i) {
-        dst->nop=src->nop;
-        dst->curop=src->curop;
-        dst->val=src->val;
-        memcpy(dst->op, src->op, sizeof(src->op));
+        dst[i]=stack->stack[i];
+        //dst->nop=src->nop;
+        //dst->curop=src->curop;
+        //dst->val=src->val;
+        //memcpy(dst->op, src->op, sizeof(src->op));
     }
-    stack->last++;
+    //stack->last++;
     return new;
 }
 
 void swap(elts, i, j)
-    STACKELT *elts;
+    int *elts;
     int i, j;
 {
-    STACKELT tmp=elts[i];
+    int tmp=elts[i];
     elts[i] = elts[j];
     elts[j] = tmp;
 }
 
 int permute_stack(array, n)
-    STACKELT *array;
+    int *array;
     int n;
 {
     int i, j, start, end;
 
     for(i=n-2; i>-1; i--) {
-        if(array[i+1].val > array[i].val) {
+        if(array[i+1] > array[i]) {
             for(j=n-1; j>i; j--){
-                if(array[j].val > array[i].val){
+                if(array[j] > array[i]){
                     // swap
                     swap(array, i, j);
                     // reverse
@@ -143,20 +168,44 @@ int permute_stack(array, n)
     return 0;
 }
 
+int gen_stacks(stack)
+    STACK *stack;
+{
+    char name[80];
+    int last=stack->last;
+    int n=1;
+    STACK *new=stack;
+    int exists=1;
+
+    printf("sorting stack...\n");
+    mergesort_stack(stack->stack, 0, last-1);
+    //print_stack(stack, 1);
+    while (exists) {
+        sprintf(name, "Stack copy %d", n);
+        new=dup_stack(new, name);
+        exists=permute_stack(new->stack, new->last);
+        if (exists) {
+            //print_stack(new, 1);
+            keep_stack(new);
+        }
+        n++;
+    }
+}
+
 
 void mergesort_stack(array, left, right)
-    STACKELT *array;
+    int *array;
     int left, right;
 {
     int mid = (left+right)/2;
     int pos=0, l=left, r=mid+1, i;
-    STACKELT tmp[right-left+1];
+    int tmp[right-left+1];
 
     if(left < right) {
         mergesort_stack(array, left, mid);
         mergesort_stack(array, mid+1,right);
         while (l <= mid && r <= right) {
-            if (array[l].val < array[r].val) {
+            if (array[l] < array[r]) {
                 tmp[pos++] = array[l++];
             }
             else {
@@ -172,41 +221,18 @@ void mergesort_stack(array, left, right)
     }
 }
 
-STACKELT *set_op_stack(stack, pos, op)
-    STACK *stack;
-    int pos;
-    OPER op;
+STACK *nth_stack(n)
+    int n;
 {
-    int size=stack->size;
-    STACKELT *pelt=stack->stack+pos;
-
-    if (pos >= size) {
-        fprintf(stderr, "set_op: stack overflow: size=%d last=%d\n", size, pos);
-        return NULL;
+    int i;
+    STACK *stack=stacks;
+    for (i=0; i<n && stack; ++i) {
+        stack=stack->next;
     }
-    pelt->op[pelt->nop++]=op;
-    pelt->op[pelt->nop]=End;
-    //pelt->val=val;
-    //stack->last++;
-    return pelt;
+    return stack;
 }
 
-STACKELT *set_ops_stack(stack, ops)
-    STACK *stack;
-    char *ops;
+int n_stacks()
 {
-    //int size=stack->size;
-    int last=stack->last;
-    int i, j;                                     /* 1st operator in on second number */
-    STACKELT *pelt=stack->stack;
-
-    printf("setting ops [%s]\n", (char *)ops);
-    for (i=1, j=0; i<last; ++i, ++j) {
-        pelt[i].nop=1;
-        pelt[i].curop=0;
-        printf("setting op [%c-%x] to pos %d[%d]\n", ops[j], ops[j], i, pelt[i].nop);
-        pelt[i].op[0]=ops[j];
-        pelt[i].op[1]=End;
-    }
-    return pelt;
+    return nstacks;
 }
diff --git a/tree.c b/tree.c
index aad074f..d00e54a 100644
--- a/tree.c
+++ b/tree.c
@@ -1,8 +1,193 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <malloc.h>
 #include "lceb.h"
 
+static TREE *trees=NULL;
+static int ntrees=0;
+static NODE *freenodes=NULL;
+static int totnodes=0;
+
+NODE *get_node()
+{
+    NODE *ret;
+
+    if (!freenodes) {
+        register int i;
+        freenodes=malloc(ALLOCSIZE*sizeof(NODE));
+        totnodes+=ALLOCSIZE;
+        printf("allocating %d nodes - total nodes=%d\n", ALLOCSIZE, totnodes);
+        for (i=0; i<ALLOCSIZE-1; ++i) {           /* create chained list */
+            (freenodes+i)->left=NULL;
+            (freenodes+i)->right=NULL;
+            (freenodes+i)->next=freenodes+i+1;
+        }
+        (freenodes+ALLOCSIZE-1)->next=NULL;
+    }
+    ret=freenodes;
+    freenodes=ret->next;
+    ret->op=Nop;
+    ret->val=-1;
+    ret->eval=-1;
+    ret->next=NULL;
+    ret->left=NULL;
+    ret->right=NULL;
+
+    return ret;
+}
+
+void free_node(node)
+    NODE *node;
+{
+    if (node->left) {
+        free_node(node->left);
+        node->left=NULL;
+    }
+    if (node->right) {
+        free_node(node->right);
+        node->right=NULL;
+    }
+    node->next=freenodes;
+    freenodes=node;
+}
+
+void print_node(node, side, depth, details)
+    NODE *node;
+    char side;
+    int depth;
+    int details;
+{
+    int i;
+
+    if (details) {
+        /* left padding */
+        for (i=0; i<=depth; ++i)
+            printf("  ");
+        printf("%c: type:%s ", side, node->type==TREE_NODE? "node": "leaf");
+        if (details) {
+            printf("op=%c val=%d eval=%d", node->op, node->val, node->eval);
+        }
+        putchar('\n');
+    } else {
+        if (node->type==TREE_NODE) {
+            printf("* ");
+        } else {
+            printf("x ");
+        }
+    }
+    if (node->left)
+        print_node(node->left, TREE_LEFT, depth+1, details);
+    if (node->right)
+        print_node(node->right, TREE_RIGHT, depth+1, details);
+}
+
+void print_tree(tree, details)
+    TREE *tree;
+    int details;
+{
+    int i;
+    if (details) {
+        printf("Tree [%s] nodes:%d leaves:%d depth:%d\n",
+               tree->name, tree->nodes, tree->leaves, tree->depth);
+
+        print_node(tree->head, TREE_TOP, 0, 1);
+    } else {
+        printf("Tree [%s] : ", tree->name);
+        print_node(tree->head, TREE_TOP, 0, 0);
+//        for (i=0; )
+        printf("\n");
+    }
+}
+
+void print_trees(details)
+    int details;
+{
+    TREE *tree=trees;
+    printf("There are %d trees:\n", ntrees);
+    while (tree) {
+        print_tree(tree, details);
+        tree=tree->next;
+    }
+}
+
+TREE *new_tree(name)
+    char *name;
+{
+    TREE *tree;
+
+    tree=malloc(sizeof(TREE));
+    strcpy(tree->name, name);
+    tree->nodes=0;
+    tree->leaves=0;
+    tree->depth=0;
+    tree->head=NULL;
+    tree->next=trees;
+    trees=tree;
+    return tree;
+}
+
+NODE *dup_node(src)
+    NODE *src;
+{
+    NODE *dst;
+    dst=get_node();
+    dst->type=src->type;
+    if (src->type==TREE_NODE) {
+        dst->op=src->op;
+        dst->left=dup_node(src->left);
+        dst->right=dup_node(src->right);
+    } else {
+        dst->val=src->val;
+    }
+    return dst;
+}
+
+/*void free_node(node)
+    NODE *node;
+{
+    if (node->type==TREE_LEAF) {
+        node->next=freenodes;
+        freenodes=node;
+    } else {
+        free_node(node->left);
+        free_node(node->right);
+        node->next=freenodes;
+        freenodes=node;
+    }
+    }*/
+
+NODE *build_tree(desc, size)
+    int *desc;
+    int size;
+{
+    NODE *root, *node;
+    NODE *nodestack[1024];      /* TODO: make it dynamic */
+    int i, curnode=0;
+
+    root=get_node();
+    root->type=TREE_NODE;
+    nodestack[curnode++]=root;
+
+    for(i=1; i<size; ++i) {
+        node = get_node();
+        if (desc[i-1]) {
+            nodestack[curnode-1]->left = node;
+        } else {
+            nodestack[curnode-1]->right = node;
+            curnode--;
+        }
+        if (desc[i]) {
+            node->type=TREE_NODE;
+            nodestack[curnode++]=node;
+        } else {
+            node->type=TREE_LEAF;
+        }
+    }
+
+    return root;
+}
+
 void gen_tree(seq, n, nb1, nb0)
     int *seq;
     int n;                      /* number of nodes */
@@ -10,15 +195,21 @@ void gen_tree(seq, n, nb1, nb0)
     int nb0;                    /* number of "0" */
 {
     int i;
+    char name[80];
+    TREE *tree;
 
-     if((nb1 + nb0) == 2*n) {   /* end */
+    if((nb1 + nb0) == 2*n) {   /* end */
         seq[2*n] = 0;
-        printf("tree=");
+        ntrees++;
+        printf("tree %d desc=", ntrees);
         for (i=0; i<=2*n; ++i)
             printf("%d", seq[i]);
         putchar('\n');
+        sprintf(name, "Tree %d", ntrees);
+        tree=new_tree(name);
+        tree->head=build_tree(seq, 2*n+1);
         return;
-     }
+    }
 
     if(nb1 >= nb0 && nb1 < n) {
         seq[nb1+nb0] = 1;
@@ -31,6 +222,22 @@ void gen_tree(seq, n, nb1, nb0)
     }
 }
 
+TREE *nth_tree(n)
+    int n;
+{
+    int i;
+    TREE *tree=trees;
+    for (i=0; i<n && tree; ++i) {
+        tree=tree->next;
+    }
+    return tree;
+}
+
+int n_trees()
+{
+    return ntrees;
+}
+
 #ifdef STANDALONE
 main(ac, av)
     int ac;
@@ -40,6 +247,7 @@ main(ac, av)
     int array[1024];
     n=atoi(av[1]);
     gen_tree(array, n, 0, 0);
+    print_trees(1);
     exit(0);
 }
 #endif