Merge pull request #116 from walkerrandolphsmith/feature/46-permutations

solve

Author: walkerrandolphsmith

leet-code/46-permutations/README.md

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+# 46-permutations
+
+## Problem Statement
+
+Given an array `nums` of **distinct integers**, return **all possible permutations** of the array.  
+You can return the answer in **any order**.
+
+### Example 1:
+
+**Input:**  
+`nums = [1, 2, 3]`
+
+**Output:**  
+`[[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]`
+
+### Example 2:
+
+**Input:**  
+`nums = [0, 1]`
+
+**Output:**  
+`[[0,1],[1,0]]`
+
+### Example 3:
+
+**Input:**  
+`nums = [1]`
+
+**Output:**  
+`[[1]]`
+
+### Constraints:
+
+- `1 <= nums.length <= 6`
+- `-10 <= nums[i] <= 10`
+- All the integers of `nums` are **unique**

leet-code/46-permutations/index.js

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+/**
+ * @param {number[]} nums
+ * @return {number[][]}
+ */
+var permute = function(nums) {
+    const backtrack = (start) => {
+        if (start === nums.length) {
+            res.push([...nums]);
+            return;
+        }
+        
+        for (let i = start; i < nums.length; i++) {
+            [nums[start], nums[i]] = [nums[i], nums[start]];
+            backtrack(start + 1);
+            [nums[start], nums[i]] = [nums[i], nums[start]];
+        }
+    };
+
+    const res = [];
+    backtrack(0);
+    return res;  
+};