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DSA_Codesheet/Cpp/MergeSort.cpp

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+#include <iostream>
+
+void merge(int arr[], int l, int m, int r) {
+    int n1 = m - l + 1;
+    int n2 = r - m;
+
+    // Create temporary arrays
+    int left[n1];
+    int right[n2];
+
+    // Copy data to temporary arrays left[] and right[]
+    for (int i = 0; i < n1; i++) {
+        left[i] = arr[l + i];
+    }
+    for (int j = 0; j < n2; j++) {
+        right[j] = arr[m + 1 + j];
+    }
+
+    // Merge the temporary arrays back into arr[l..r]
+    int i = 0; // Initial index of first subarray
+    int j = 0; // Initial index of second subarray
+    int k = l; // Initial index of merged subarray
+
+    while (i < n1 && j < n2) {
+        if (left[i] <= right[j]) {
+            arr[k] = left[i];
+            i++;
+        } else {
+            arr[k] = right[j];
+            j++;
+        }
+        k++;
+    }
+
+    // Copy the remaining elements of left[], if any
+    while (i < n1) {
+        arr[k] = left[i];
+        i++;
+        k++;
+    }
+
+    // Copy the remaining elements of right[], if any
+    while (j < n2) {
+        arr[k] = right[j];
+        j++;
+        k++;
+    }
+}
+
+void mergeSort(int arr[], int l, int r) {
+    if (l < r) {
+        int m = l + (r - l) / 2;
+
+        // Sort first and second halves
+        mergeSort(arr, l, m);
+        mergeSort(arr, m + 1, r);
+
+        // Merge the sorted halves
+        merge(arr, l, m, r);
+    }
+}
+
+int main() {
+    int arr[] = {12, 11, 13, 5, 6, 7};
+    int arr_size = sizeof(arr) / sizeof(arr[0]);
+
+    std::cout << "Original array: ";
+    for (int i = 0; i < arr_size; i++) {
+        std::cout << arr[i] << " ";
+    }
+    std::cout << std::endl;
+
+    // Perform merge sort
+    mergeSort(arr, 0, arr_size - 1);
+
+    std::cout << "Sorted array: ";
+    for (int i = 0; i < arr_size; i++) {
+        std::cout << arr[i] << " ";
+    }
+    std::cout << std::endl;
+
+    return 0;
+}