solving first problem

lab13/2.c

@@ -0,0 +1,29 @@
+#include <stdio.h>
+
+long int f[1000] = {0};
+
+unsigned long int fib(unsigned long int n) {
+    unsigned int i;
+
+    f[0] = 0;
+    f[1] = 1;
+
+    if (f[n]) {
+        printf("Reused\n");
+        return (unsigned long int ) f[n];
+    }
+
+    if (n > 2) {
+        for (i = 2; i <= n; i++) {
+            if (!f[i]) f[i] = f[i - 1] + f[i - 2];
+        }
+    }
+    return (unsigned long int ) f[n];
+}
+
+int main() {
+    printf("%ld\n", fib(11));
+    printf("%ld\n", fib(10));
+    printf("%ld\n", fib(12));
+    return 0;
+}