Problem 49

49.c

@@ -0,0 +1,45 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <math.h>
+#include "primes.h"
+
+bool arePermutations (int a, int b, int c) {
+    int aDigOcc[10] = {0};
+    int bDigOcc[10] = {0};
+    int cDigOcc[10] = {0};
+
+    for (int i = 0; i < 4; i++) {
+        aDigOcc[a % 10]++;
+        a /= 10;
+
+        bDigOcc[b % 10]++;
+        b /= 10;
+
+        cDigOcc[c % 10]++;
+        c /= 10;
+    }
+
+    for (int i = 0; i < 10; i++) {
+        if (aDigOcc[i] != bDigOcc[i] || bDigOcc[i] != cDigOcc[i] || cDigOcc[i] != aDigOcc[i])
+            return false;
+    } 
+    return true;
+}
+
+int main () {
+    long* primes;
+    bool* primesTable;
+    listOfPrimes (10000, &primes, &primesTable);
+
+    int sum = 0;
+    for (int r = 1; r < 4499; r++) {
+        for (int n = 1000; n < 9999 - 2 * r; n++) {
+            int a = n;
+            int b = n + r;
+            int c = b + r;
+            if (primesTable[a] && primesTable[b] && primesTable[c] && arePermutations (a, b, c))
+                printf ("%d%d%d\n", a, b, c); 
+        }
+    }
+}