implement merge sort

merge_sort.cpp

@@ -0,0 +1,69 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+void merge(vector<int>& arr, int l, int mid, int r){
+	int l1 = mid - l + 1;
+	int l2 = r - mid;
+	vector<int> a1;
+	vector<int> a2;
+
+	for(int i = 0; i < l1; i++) {
+		a1.emplace_back(arr[l + i]);
+	}
+	for(int i = 0; i < l2; i++) {
+		a2.emplace_back(arr[mid + 1 + i]);
+	}
+
+	int i = 0, j = 0, k = l;
+
+	while(i < l1 && j < l2) {
+		if(a1[i] < a2[j]) {
+			arr[k++] = a1[i++];
+		}else {
+			arr[k++] = a2[j++];
+		}
+	}
+
+	while(i < l1) {
+		arr[k++] = a1[i++];
+	}
+	while(j < l2) {
+		arr[k++] = a2[j++];
+	}
+}
+
+void mergeSort(vector<int>& arr, int l, int r) {
+
+	if(l < r) {
+		int mid = (l + r) / 2;
+		mergeSort(arr, l, mid);
+		mergeSort(arr, mid + 1, r);
+
+		merge(arr, l, mid, r);
+	}
+
+
+}
+
+int main() {
+	int n;
+	cin>>n;
+	int count = 0;
+
+	vector<int> arr;
+
+	for(int i = 0; i < n; i++) {
+		int x;
+		cin>>x;
+
+		arr.emplace_back(x);
+	}
+
+	mergeSort(arr, 0, n-1);
+
+	for(auto it: arr) {
+		cout<<it<<" ";
+	}
+	cout<<endl;
+	cout<<count<<endl;
+}