Create 0912-sort-an-array.js

Added solution for Sorting an array in JS.

Author: aadil42

javascript/0912-sort-an-array.js

@@ -0,0 +1,54 @@
+/**
+ * https://leetcode.com/problems/sort-an-array/
+ * Merge Sort
+ * Time O(n*log(n)) | Space O(n)
+ * @param {number[]} nums
+ * @return {number[]}
+ */
+var sortArray = function(nums) {
+    
+    const merge = (left, mid, right) => {
+        const arr1 = nums.slice(left, mid+1);
+        const arr2 = nums.slice(mid+1, right + 1);
+        
+        let p1 = 0; 
+        let p2 = 0;
+        let gp = left;
+
+        while(p1 < arr1.length && p2 < arr2.length) {
+            if(arr1[p1] < arr2[p2]) {
+                nums[gp] = arr1[p1];
+                p1++;
+            } else {
+                nums[gp] = arr2[p2];
+                p2++;
+            }
+            gp++;
+        }
+
+        while(p1 < arr1.length) {
+            nums[gp] = arr1[p1];
+            p1++;
+            gp++;
+        }
+
+        while(p2 < arr2.length) {
+            nums[gp] = arr2[p2];
+            p2++;
+            gp++;
+        }
+        return nums;
+    }  
+
+    const mergeSort = (left, right) => {
+
+        if(left === right) return nums;
+        
+        const mid = Math.floor((left+right)/2);
+        mergeSort(left, mid);
+        mergeSort(mid+1, right);
+        return merge(left, mid, right);
+    }
+
+    return mergeSort(0, nums.length  - 1);
+};