Create 0912-sort-an-array.cpp

Author: Piyush-Deshmukh

cpp/0912-sort-an-array.cpp

@@ -0,0 +1,52 @@
+/*
+    Given an array of integers nums, sort the array in ascending order and return it.
+    Ex. nums = [5,2,3,1] -> [1,2,3,5]
+
+    Use Merge sort to sort the array.
+
+    Time - O(nlogn)
+    Space - O(n)
+*/
+
+class Solution {
+  private:
+    void merge(vector<int> &nums, int low, int mid, int high) {
+        if(low >= high) 
+            return;
+        
+        int l = low, r = mid + 1, k = 0, size = high - low + 1;
+        vector<int> sorted(size, 0);
+        
+        while (l <= mid and r <= high){
+            if(nums[l] < nums[r])
+                sorted[k++] = nums[l++];
+            else
+                sorted[k++] = nums[r++];
+        }
+
+        while(l <= mid) 
+            sorted[k++] = nums[l++];
+        while(r <= high) 
+            sorted[k++] = nums[r++];
+        
+        for(k = 0; k < size; k++)
+            nums[k + low] = sorted[k];
+    }
+
+    void mergeSort(vector<int>& nums, int low, int high){
+        if(low >= high) 
+            return;
+	    
+        int mid = low + (high - low) / 2;
+	    
+        mergeSort(nums, low, mid);
+	    mergeSort(nums, mid + 1, high);
+	    merge(nums, low, mid, high);
+    }
+
+public:
+    vector<int> sortArray(vector<int>& nums) {
+        mergeSort(nums, 0, nums.size()-1);
+        return nums;
+    }
+};