From c849ae308d0ebe96bee0369325cd544f6cb5a5f6 Mon Sep 17 00:00:00 2001
From: Aerex <nanaus13@yahoo.com>
Date: Tue, 18 Feb 2020 10:32:25 -0600
Subject: [PATCH] feat: Added permutations problem in js

---
 permutations/nodejs/index.js | 58 ++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 permutations/nodejs/index.js

diff --git a/permutations/nodejs/index.js b/permutations/nodejs/index.js
new file mode 100644
index 0000000..249352b
--- /dev/null
+++ b/permutations/nodejs/index.js
@@ -0,0 +1,58 @@
+/*
+ * Given a collection of distinct integers, return all possible permutations.
+ * Example:
+ *
+ * Input: [1,2,3]
+ * Output:
+ *
+ * [
+ *    [1,2,3],
+ *    [1,3,2],
+ *    [2,1,3],
+ *    [2,3,1],
+ *    [3,1,2],
+ *    [3,2,1]
+ *
+ *  ]
+*/
+
+const { assert } = require('../../util/js');
+
+/**
+ * @param {number[]} nums
+ * @return {number[][]}
+ */
+const permute = function(nums) {
+    
+    const permuRecursive = (soFar, rest, perm) => {
+        if (rest.length === 0) {
+            perm.push(soFar);
+        }
+        
+        for(let i = 0; i < rest.length; i++) {
+            const rem = [...rest.slice(0, i), ...rest.slice(i+1)];
+            permuRecursive([...soFar, rest[i]],  rem, perm);
+        }
+    }
+    const result = [];
+    permuRecursive([], nums, result);
+    return result;
+    
+};
+
+/* Test Case 1
+ * Input: [1,2,3]
+ * Output:
+ * [
+ *    [1,2,3],
+ *    [1,3,2],
+ *    [2,1,3],
+ *    [2,3,1],
+ *    [3,1,2],
+ *    [3,2,1]
+ *
+ *  ]
+ */
+x = [1,2,3];
+sol = [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]];
+assert(JSON.stringify(permute(x)) === JSON.stringify(sol), `Output: ${JSON.stringify(sol)}`);