Initial Commit - days 01-12

day11/ex2-c.c

@@ -0,0 +1,219 @@
+/* ex1-c: Advent2020 game, day 10/game 1
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct seats {
+    char status;
+    unsigned neighbours;
+};
+
+struct plane {
+    unsigned nrow;
+    unsigned ncol;
+    unsigned size;
+    unsigned last;
+    unsigned seated;
+    struct seats *seats;
+};
+
+#define BLOCKSIZE	(10*1024) /* number of elements for realloc() */
+
+void print_count(plane)
+    struct plane *plane;
+{
+    unsigned i, psize=plane->last;
+    unsigned ncols=plane->ncol;
+    struct seats *ptr=plane->seats;
+
+    for (i=0; i<psize; ++i) {
+        if (i>0 && !(i%ncols)) {
+            putchar('\n');
+        }
+        printf("%2d ", (ptr+i)->neighbours);
+    }
+    putchar('\n');
+}
+
+void print_seats(plane)
+    struct plane *plane;
+{
+    unsigned i, psize=plane->last;
+    unsigned ncols=plane->ncol, nrow=plane->nrow;
+    struct seats *ptr=plane->seats;
+
+    fprintf(stderr, "PLANE: address=%p seat=%p rows=%d cols=%d size=%d\n",
+            plane, ptr, nrow, ncols, psize);
+    for (i=0; i<psize; ++i) {
+        if (i>0 && !(i%ncols)) {
+            putchar('\n');
+        }
+        printf("%c ", (ptr+i)->status);
+    }
+    putchar('\n');
+}
+
+void reset_seats(plane)
+    struct plane *plane;
+{
+    unsigned i, last=plane->last;
+    struct seats *seat=plane->seats;
+
+    for (i=0; i<last; ++i, ++seat)
+        seat->neighbours=0;
+}
+
+struct plane *add_row(plane, c)
+    struct plane *plane;
+    char *c;
+{
+    unsigned size;
+
+    if (!plane) {
+        plane=malloc(sizeof(struct plane));
+        plane->seats=malloc(sizeof(struct seats)*BLOCKSIZE);
+        plane->size=BLOCKSIZE;
+        plane->ncol=strlen(c)-1;
+        plane->last=0;
+    }
+    size=plane->size;
+
+    while (*c) {
+        if (*c != '\n') {
+            if (plane->last == size) {
+                size+=BLOCKSIZE;
+                plane->size=size;
+                plane->seats=realloc(plane->seats, sizeof(struct seats)*size);
+            }
+            plane->seats[plane->last].status=*c;
+            plane->last++;
+            plane->nrow=plane->last/plane->ncol;
+        }
+        c++;
+    }
+
+    return plane;
+}
+
+int sit(plane)
+    struct plane *plane;
+{
+    unsigned changed=0, cur, seated=0;
+    unsigned last=plane->last;
+    struct seats *seats=plane->seats;
+
+    for (cur=0; cur<last; ++cur) {
+        switch (seats[cur].status) {
+            case '.':
+                break;
+            case '#':
+                if (seats[cur].neighbours >= 5) {
+                    seats[cur].status='L';
+                    changed++;
+                } else {
+                    seated++;
+                }
+                break;
+            case 'L':
+                if (seats[cur].neighbours == 0) {
+                    seats[cur].status='#';
+                    changed++;
+                    seated++;
+                }
+                break;
+        }
+    }
+    plane->seated=seated;
+    return changed;
+}
+
+int calc(plane)
+    struct plane *plane;
+{
+    unsigned row, col, cur;
+    unsigned last=plane->last;
+    int cols=plane->ncol;
+    int rows=plane->nrow;
+    int c, r;
+    struct seats *seats=plane->seats;
+    reset_seats(plane);
+    for (cur=0; cur<last; ++cur) {
+        if (seats[cur].status == '#') {
+            row=cur/cols;
+            col=cur%cols;
+
+            // up left
+            for (r=row-1, c=col-1; r>=0 && c>=0; --r, --c) {
+                seats[r*cols + c].neighbours++;
+                if (seats[r*cols + c].status != '.')
+                    break;
+            }
+            // up right
+            for (r=row-1, c=col+1; r>=0 && c<cols; --r, ++c) {
+                seats[r*cols + c].neighbours++;
+                if (seats[r*cols + c].status != '.')
+                    break;
+            }
+            // down left
+            for (r=row+1, c=col-1; r<rows && c>=0; ++r, --c) {
+                seats[r*cols + c].neighbours++;
+                if (seats[r*cols + c].status != '.')
+                    break;
+            }
+            // down right
+            for (r=row+1, c=col+1; r<rows && c<cols; ++r, ++c) {
+                seats[r*cols + c].neighbours++;
+                if (seats[r*cols + c].status != '.')
+                    break;
+            }
+            // up
+            for (r=row-1, c=col; r>=0; --r) {
+                seats[r*cols + c].neighbours++;
+                if (seats[r*cols + c].status != '.')
+                    break;
+            }
+            // down
+            for (r=row+1, c=col; r<rows; ++r) {
+                seats[r*cols + c].neighbours++;
+                if (seats[r*cols + c].status != '.')
+                    break;
+            }
+            // left
+            for (r=row, c=col-1; c>=0; --c) {
+                seats[r*cols + c].neighbours++;
+                if (seats[r*cols + c].status != '.')
+                    break;
+            }
+            // right
+            for (r=row, c=col+1; c<cols; ++c) {
+                seats[r*cols + c].neighbours++;
+                if (seats[r*cols + c].status != '.')
+                    break;
+            }
+        }
+    }
+    return 1;
+}
+
+int main(ac, av)
+    int ac;
+    char **av;
+{
+    char line[512];
+    struct plane *plane=NULL;
+
+    while (fgets(line, sizeof line, stdin)) {
+        plane=add_row(plane, line);
+    }
+
+    do {
+        calc(plane);
+        //print_seats(plane);
+        //print_count(plane);
+    } while (sit(plane) > 0);
+
+    printf("%s : res=%d\n", *av, plane->seated);
+    exit (0);
+}