Data commit

Task/EKG-sequence-convergence/C/ekg-sequence-convergence.c

@@ -0,0 +1,75 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#define TRUE 1
+#define FALSE 0
+#define LIMIT 100
+
+typedef int bool;
+
+int compareInts(const void *a, const void *b) {
+    int aa = *(int *)a;
+    int bb = *(int *)b;
+    return aa - bb;
+}
+
+bool contains(int a[], int b, size_t len) {
+    int i;
+    for (i = 0; i < len; ++i) {
+        if (a[i] == b) return TRUE;
+    }
+    return FALSE;
+}
+
+int gcd(int a, int b) {
+    while (a != b) {
+        if (a > b)
+            a -= b;
+        else
+            b -= a;
+    }
+    return a;
+}
+
+bool areSame(int s[], int t[], size_t len) {
+    int i;
+    qsort(s, len, sizeof(int), compareInts);
+    qsort(t, len, sizeof(int), compareInts);
+    for (i = 0; i < len; ++i) {
+        if (s[i] != t[i]) return FALSE;
+    }
+    return TRUE;
+}
+
+int main() {
+    int s, n, i;
+    int starts[5] = {2, 5, 7, 9, 10};
+    int ekg[5][LIMIT];
+    for (s = 0; s < 5; ++s) {
+        ekg[s][0] = 1;
+        ekg[s][1] = starts[s];
+        for (n = 2; n < LIMIT; ++n) {
+            for (i = 2; ; ++i) {
+                // a potential sequence member cannot already have been used
+                // and must have a factor in common with previous member
+                if (!contains(ekg[s], i, n) && gcd(ekg[s][n - 1], i) > 1) {
+                    ekg[s][n] = i;
+                    break;
+                }
+            }
+        }
+        printf("EKG(%2d): [", starts[s]);
+        for (i = 0; i < 30; ++i) printf("%d ", ekg[s][i]);
+        printf("\b]\n");
+    }
+
+    // now compare EKG5 and EKG7 for convergence
+    for (i = 2; i < LIMIT; ++i) {
+        if (ekg[1][i] == ekg[2][i] && areSame(ekg[1], ekg[2], i)) {
+            printf("\nEKG(5) and EKG(7) converge at term %d\n", i + 1);
+            return 0;
+        }
+    }
+    printf("\nEKG5(5) and EKG(7) do not converge within %d terms\n", LIMIT);
+    return 0;
+}