Problem 55

55.c

@@ -0,0 +1,39 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+long long reverse (long long n) {
+    long long num = n;
+    long long reversed = 0;
+    while (num > 0) {
+        reversed = reversed * 10 + num % 10;
+        num /= 10;
+    }
+    return reversed;
+}
+
+bool isPalindrome(long long n) {
+    return n == reverse (n);
+}
+
+bool isLychrel (int n) {
+    long long num = n;
+    int lychrel = true;
+    int count = 0;
+    while (lychrel && count < 50) {
+        num += reverse (num);
+        lychrel = !isPalindrome (num);
+        count++;
+    }
+    return lychrel;
+}
+
+int main () {
+    int lychrels = 0;
+    for (int i = 1; i < 10000; i++) {
+        bool lychrel = isLychrel (i);
+        if (lychrel)
+            lychrels++;
+    }
+    printf ("%d Lychrels\n", lychrels);
+}