提出 足立航大

src/gcd.d

@@ -0,0 +1,38 @@
+#include <stdio.h>
+
+const int n = 1000;
+
+unsigned int Euclidean_gcd_rec(unsigned int x, unsigned int y){
+ if(x==0) return y;
+ return Euclidean_gcd_rec(y % x, x);
+}
+
+/*
+unsigned int Euclidean_gcd_itr(unsigned int x, unsigned int y){
+}
+
+unsigned int binary_gcd_rec(unsigned int x, unsigned int y){
+}
+
+unsigned int binary_gcd_itr(unsigned int x, unsigned int y){
+}
+*/
+
+
+int main(){
+  unsigned int i, j, c;
+
+
+  c = 0;
+  for(i = 1; i <= n; i++){
+    for(j = i + 1; j <= n; j++){
+      if(Euclidean_gcd_rec(i, j) == 1){
+        c++;
+      }
+    }
+  }
+  c = 2 * c + 1;
+
+  printf("%f\n", (double) c / (n * n));
+  return 0;
+}