Create merge_sort.cpp

merge_sort.cpp

@@ -0,0 +1,108 @@
+#include<iostream> 
+using namespace std; 
+
+// Merges two subarrays of arr[]. 
+// First subarray is arr[l..m] 
+// Second subarray is arr[m+1..r] 
+void merge(int arr[], int l, int m, int r) 
+{ 
+    int n1 = m - l + 1; 
+    int n2 = r - m; 
+
+    // Create temp arrays  
+    int L[n1], R[n2]; 
+
+    // Copy data to temp arrays L[] and R[]  
+    for(int i = 0; i < n1; i++) 
+        L[i] = arr[l + i]; 
+    for(int j = 0; j < n2; j++) 
+        R[j] = arr[m + 1 + j]; 
+
+    // Merge the temp arrays back into arr[l..r] 
+
+    // Initial index of first subarray 
+    int i = 0;  
+
+    // Initial index of second subarray 
+    int j = 0;  
+
+    // Initial index of merged subarray 
+    int k = l; 
+
+    while (i < n1 && j < n2) 
+    { 
+        if (L[i] <= R[j])  
+        { 
+            arr[k] = L[i]; 
+            i++; 
+        } 
+        else 
+        { 
+            arr[k] = R[j]; 
+            j++; 
+        } 
+        k++; 
+    } 
+
+    // Copy the remaining elements of 
+    // L[], if there are any  
+    while (i < n1)  
+    { 
+        arr[k] = L[i]; 
+        i++; 
+        k++; 
+    } 
+
+    // Copy the remaining elements of 
+    // R[], if there are any  
+    while (j < n2) 
+    { 
+        arr[k] = R[j]; 
+        j++; 
+        k++; 
+    } 
+} 
+
+// l is for left index and r is  
+// right index of the sub-array 
+// of arr to be sorted */ 
+void mergeSort(int arr[], int l, int r) 
+{ 
+    if (l < r) 
+    { 
+
+        // Same as (l+r)/2, but avoids  
+        // overflow for large l and h 
+        int m = l + (r - l) / 2; 
+
+        // Sort first and second halves 
+        mergeSort(arr, l, m); 
+        mergeSort(arr, m + 1, r); 
+
+        merge(arr, l, m, r); 
+    } 
+} 
+
+// UTILITY FUNCTIONS  
+// Function to print an array  
+void printArray(int A[], int size) 
+{ 
+    for(int i = 0; i < size; i++) 
+        cout << A[i] << " "; 
+} 
+
+// Driver code 
+int main() 
+{ 
+    int arr[] = { 12, 11, 13, 5, 6, 7 }; 
+    int arr_size = sizeof(arr) / sizeof(arr[0]); 
+
+    cout << "Given array is \n"; 
+    printArray(arr, arr_size); 
+
+    mergeSort(arr, 0, arr_size - 1); 
+
+    cout << "\nSorted array is \n"; 
+    printArray(arr, arr_size); 
+    return 0; 
+}