fixed algorithm

Author: taisukef

shuffle.js

@@ -1,12 +1,10 @@
 import { rnd } from "./rnd.js";
 
-const shuffle = (array) => {
-    for (let i = 0; i < array.length; i++) {
-		const n = rnd(array.length);
-		const tmp = array[i];
+export const shuffle = (array) => {
+  for (let i = array.length - 1; i >= 1; i--) {
+    const n = rnd(i + 1);
+  	const tmp = array[i];
 		array[i] = array[n];
 		array[n] = tmp;
 	}
 };
-
-export { shuffle };