Initial data commit

Task/Fortunate-numbers/C/fortunate-numbers.c

@@ -0,0 +1,73 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <gmp.h>
+
+int *primeSieve(int limit, int *length) {
+    int i, p, *primes;
+    int j, pc = 0;
+    limit++;
+    // True denotes composite, false denotes prime.
+    bool *c = calloc(limit, sizeof(bool)); // all false by default
+    c[0] = true;
+    c[1] = true;
+    for (i = 4; i < limit; i += 2) c[i] = true;
+    p = 3; // Start from 3.
+    while (true) {
+        int p2 = p * p;
+        if (p2 >= limit) break;
+        for (i = p2; i < limit; i += 2 * p) c[i] = true;
+        while (true) {
+            p += 2;
+            if (!c[p]) break;
+        }
+    }
+    for (i = 0; i < limit; ++i) {
+        if (!c[i]) ++pc;
+    }
+    primes = (int *)malloc(pc * sizeof(int));
+    for (i = 0, j = 0; i < limit; ++i) {
+        if (!c[i]) primes[j++] = i;
+    }
+    free(c);
+    *length = pc;
+    return primes;
+}
+
+int compare(const void* a, const void* b) {
+    int arg1 = *(const int*)a;
+    int arg2 = *(const int*)b;
+    if (arg1 < arg2) return -1;
+    if (arg1 > arg2) return 1;
+    return 0;
+}
+
+int main() {
+    int i, j, f, pc, ac, limit = 379, fc = 0;
+    int *primes = primeSieve(limit, &pc);
+    int fortunates[80];
+    mpz_t primorial, temp;
+    mpz_init_set_ui(primorial, 1);
+    mpz_init(temp);
+    for (i = 0; i < pc; ++i) {
+        mpz_mul_ui(primorial, primorial, primes[i]);
+        for (j = 3; ; j += 2) {
+            mpz_add_ui(temp, primorial, j);
+            if (mpz_probab_prime_p(temp, 15) > 0) {
+                fortunates[fc++] = j;
+                break;
+            }
+        }
+    }
+    qsort(fortunates, fc, sizeof(int), compare);
+    printf("After sorting, the first 50 distinct fortunate numbers are:\n");
+    for (i = 0, ac = 0; ac < 50; ++i) {
+       f = fortunates[i];
+       if (i > 0 && f == fortunates[i-1]) continue;
+       printf("%3d ", f);
+       ++ac;
+       if (!(ac % 10)) printf("\n");
+    }
+    free(primes);
+    return 0;
+}