Merge pull request #8 from SaloniSingh1601/master

Merge_sort algo in c++

merge_sort.cpp

@@ -0,0 +1,68 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+void merge(int arr[], int l, int m, int r) {
+    int nl = m - l + 1;
+    int nr = r - m;
+    int larr[nl], rarr[nr];
+    for (int i = 0; i < nl; i++) {
+        larr[i] = arr[l + i];
+    }
+    for (int j = 0; j < nr; j++) {
+        rarr[j] = arr[m + 1 + j];
+    }
+    int i = 0;
+    int j = 0;
+    int k = l;
+    while (i < nl && j < nr) {
+        if (larr[i] <= rarr[j]) {
+            arr[k] = larr[i];
+            i++;
+        }
+        else {
+            arr[k] = rarr[j];
+            j++;
+        }
+        k++;
+    }
+    while (i < nl) {
+        arr[k] = larr[i];
+        i++;
+        k++;
+    }
+    while (j < nr) {
+        arr[k] = rarr[j];
+        j++;
+        k++;
+    }
+}
+
+void MergeSort(int arr[], int l, int r) {
+    int m = l + ((r - l) / 2);
+    if (l < r) {
+        MergeSort(arr, l, m);
+        MergeSort(arr, m + 1, r);
+        merge(arr, l, m, r);
+    }
+}
+
+int main(int argc, char* argv[]) {
+    freopen(argv[1], "r", stdin);
+    freopen("mergesort.txt", "w", stdout);
+    vector <int> v ;
+    int s;
+    while (cin>>s) {
+        v.push_back(s);
+    }
+    int n = v.size();
+    int arr[n];
+    for(int i = 0; i < n; i++){
+        arr[i] = v[i];
+    }
+    MergeSort(arr, 0, n - 1);
+    for (int i = 0; i < n-1; i++) {
+        cout << arr[i] << endl;
+    }
+    cout<<arr[n-1];
+    return 0;
+}