rename repo, subdir for yearly challenges

2020/day14/ex2-c.c

@@ -0,0 +1,163 @@
+/* ex2-c: Advent2020 game, day 14/game 2
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct memcell {
+    unsigned long long num;
+    unsigned long long val;
+    struct memcell *next;       /* if collision */
+};
+struct hashtable {
+    struct memcell *first;
+};
+
+#define HASHSIZE	1024
+#define HASH(i)		((i)%HASHSIZE)
+
+static struct hashtable mem[HASHSIZE];
+static char maskstr[128];
+static unsigned long long exp[128];
+
+struct memcell *get_cell(cell)
+    unsigned long long cell;
+{
+    struct memcell *p=mem[HASH(cell)].first;
+
+    while (p && p->num != cell)
+        p=p->next;
+    return p;
+}
+
+struct memcell *set_cell(cell, val)
+    unsigned long long cell;
+    unsigned long long val;
+{
+    struct memcell *p=get_cell(cell);
+    unsigned hash=HASH(cell);
+
+    if (!p) {
+        p=malloc(sizeof (struct memcell));
+        p->next=mem[hash].first;
+        mem[hash].first=p;
+    }
+    p->num=cell;
+    p->val=val;
+    return p;
+}
+
+unsigned long long print_cells()
+{
+    unsigned i;
+    unsigned long long res=0;
+    struct memcell *p;
+
+    puts("CELLS :");
+    for (i=0; i<HASHSIZE; ++i) {
+        p=mem[i].first;
+        while (p) {
+            printf("[%llu]=%llu\n", p->num, p->val);
+            res+=p->val;
+            p=p->next;
+        }
+    }
+    return res;
+}
+
+unsigned long long calc_cells()
+{
+    unsigned i;
+    unsigned long long res=0;
+    struct memcell *p;
+
+    for (i=0; i<HASHSIZE; ++i) {
+        p=mem[i].first;
+        while (p) {
+            res+=p->val;
+            p=p->next;
+        }
+    }
+    return res;
+}
+
+unsigned long long ormask(str)
+    char *str;
+{
+    char *p;
+    unsigned long long mask=0, exp=1;
+
+    for (p=str+strlen(str)-1; p>=str; p--, exp<<=1)
+        if (*p == '1')
+            mask+=exp;
+    return mask;
+}
+
+unsigned long long andmask(str)
+    char *str;
+{
+    char *p;
+    unsigned long long mask=0, exp=1;
+
+    for (p=str+strlen(str)-1; p>=str; p--, exp<<=1)
+        if (*p != 'X')
+            mask+=exp;
+    return mask;
+}
+
+void print_exp()
+{
+    int i;
+    for (i=0; exp[i]; ++i) {
+        printf("%2d: %llu", i, exp[i]);
+    }
+
+}
+
+void calc_masks(mempos, val, cur)
+    unsigned long mempos, val;
+    int cur;
+{
+    unsigned long long mask=exp[cur];
+
+    if (mask == 0) {
+        set_cell(mempos, val);
+        return;
+    }
+    calc_masks(mempos, val, cur+1);
+    calc_masks(mempos+mask, val, cur+1);
+}
+
+int main(ac, av)
+    int ac;
+    char **av;
+{
+    char line[1024];
+    unsigned long long val, mempos, or, and;
+    int i=0, j;
+
+    while (fgets(line, sizeof line, stdin)) {
+        if (!strncmp(line, "mask", 4)) {
+            sscanf(line, "%*[^01X]%s", maskstr);
+            or=ormask(maskstr);
+            and=andmask(maskstr);
+            val=1; j=0;
+            for (i=strlen(maskstr)-1; i>=0; --i) {
+                if (maskstr[i]=='X') {
+                    exp[j]=val;
+                    j++;
+                }
+
+                val<<=1;
+            }
+            exp[j]=0;
+        } else {
+            sscanf(line, "%*[^0-9]%llu] = %llu", &mempos, &val);
+            mempos=(mempos|or)&and;
+            calc_masks(mempos, val, 0);
+        }
+    }
+    printf("%s : res=%llu\n", *av, calc_cells());
+    exit (0);
+}