Data commit

Task/Kolakoski-sequence/C/kolakoski-sequence.c

@@ -0,0 +1,88 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#define TRUE 1
+#define FALSE 0
+
+typedef int bool;
+
+int next_in_cycle(int *c, int len, int index) {
+    return c[index % len];
+}
+
+void kolakoski(int *c, int *s, int clen, int slen) {
+    int i = 0, j, k = 0;
+    while (TRUE) {
+        s[i] = next_in_cycle(c, clen, k);
+        if (s[k] > 1) {
+            for (j = 1; j < s[k]; ++j) {
+                if (++i == slen) return;
+                s[i] = s[i - 1];
+            }
+        }
+        if (++i == slen) return;
+        k++;
+    }
+}
+
+bool possible_kolakoski(int *s, int len) {
+    int i, j = 0, prev = s[0], count = 1;
+    int *rle = calloc(len, sizeof(int));
+    bool result = TRUE;
+    for (i = 1; i < len; ++i) {
+        if (s[i] == prev) {
+            count++;
+        }
+        else {
+            rle[j++] = count;
+            count = 1;
+            prev = s[i];
+        }
+    }
+    /* no point adding final 'count' to rle as we're not going to compare it anyway */
+    for (i = 0; i < j; i++) {
+        if (rle[i] != s[i]) {
+           result = FALSE;
+           break;
+        }
+    }
+    free(rle);
+    return result;
+}
+
+void print_array(int *a, int len) {
+    int i;
+    printf("[");
+    for (i = 0; i < len; ++i) {
+       printf("%d", a[i]);
+       if (i < len - 1) printf(", ");
+    }
+    printf("]");
+}
+
+int main() {
+    int i, clen, slen, *s;
+    int c0[2] = {1, 2};
+    int c1[2] = {2, 1};
+    int c2[4] = {1, 3, 1, 2};
+    int c3[4] = {1, 3, 2, 1};
+    int *cs[4] = {c0, c1, c2, c3};
+    bool p;
+    int clens[4] = {2, 2, 4, 4};
+    int slens[4] = {20, 20, 30, 30};
+    for (i = 0; i < 4; ++i) {
+        clen = clens[i];
+        slen = slens[i];
+        s = calloc(slen, sizeof(int));
+        kolakoski(cs[i], s, clen, slen);
+        printf("First %d members of the sequence generated by ", slen);
+        print_array(cs[i], clen);
+        printf(":\n");
+        print_array(s, slen);
+        printf("\n");
+        p = possible_kolakoski(s, slen);
+        printf("Possible Kolakoski sequence? %s\n\n", p ? "True" : "False");
+        free(s);
+    }
+    return 0;
+}