C语言自顶向下的二路归并排序算法,C++实现自顶向下的归并排序算法

以下是C语言自顶向下的二路归并排序算法的实现：

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

void merge(int arr[], int left, int mid, int right) {
    int n1 = mid - left + 1;
    int n2 = right - mid;
    int *L = (int*) malloc(sizeof(int) * n1);
    int *R = (int*) malloc(sizeof(int) * n2);
    int i, j, k;

    for (i = 0; i < n1; i++) {
        L[i] = arr[left + i];
    }
    for (j = 0; j < n2; j++) {
        R[j] = arr[mid + 1 + j];
    }

    i = j = 0;
    k = left;

    while (i < n1 && j < n2) {
        if (L[i] <= R[j]) {
            arr[k++] = L[i++];
        }
        else {
            arr[k++] = R[j++];
        }
    }

    while (i < n1) {
        arr[k++] = L[i++];
    }

    while (j < n2) {
        arr[k++] = R[j++];
    }

    free(L);
    free(R);
}

void mergeSort(int arr[], int left, int right) {
    if (left >= right) return;
    int mid = (left + right) / 2;
    mergeSort(arr, left, mid);
    mergeSort(arr, mid + 1, right);
    merge(arr, left, mid, right);
}

int main() {
    int n = 10, i;
    int arr[] = {5, 4, 8, 3, 1, 9, 6, 2, 7, 0};
    srand(time(NULL));
    printf("Original array: ");
    for (i = 0; i < n; i++) {
        printf("%d ", arr[i]);
    }
    printf("\n");

    mergeSort(arr, 0, n-1);

    printf("Sorted array: ");
    for (i = 0; i < n; i++) {
        printf("%d ", arr[i]);
    }
    printf("\n");

    return 0;
}

以下是C++实现自顶向下的归并排序算法的代码：

#include <iostream>
using namespace std;

void merge(int arr[], int left, int mid, int right) {
    int n1 = mid - left + 1;
    int n2 = right - mid;
    int *L = new int[n1];
    int *R = new int[n2];
    int i, j, k;

    for (i = 0; i < n1; i++) {
        L[i] = arr[left + i];
    }
    for (j = 0; j < n2; j++) {
        R[j] = arr[mid + 1 + j];
    }

    i = j = 0;
    k = left;

    while (i < n1 && j < n2) {
        if (L[i] <= R[j]) {
            arr[k++] = L[i++];
        }
        else {
            arr[k++] = R[j++];
        }
    }

    while (i < n1) {
        arr[k++] = L[i++];
    }

    while (j < n2) {
        arr[k++] = R[j++];
    }

    delete[] L;
    delete[] R;
}

void mergeSort(int arr[], int left, int right) {
    if (left >= right) return;
    int mid = (left + right) / 2;
    mergeSort(arr, left, mid);
    mergeSort(arr, mid + 1, right);
    merge(arr, left, mid, right);
}

int main() {
    int n = 10, i;
    int arr[] = {5, 4, 8, 3, 1, 9, 6, 2, 7, 0};
    srand(time(NULL));
    cout << "Original array: ";
    for (i = 0; i < n; i++) {
        cout << arr[i] << " ";
    }
    cout << endl;

    mergeSort(arr, 0, n-1);

    cout << "Sorted array: ";
    for (i = 0; i < n; i++) {
        cout << arr[i] << " ";
    }
    cout << endl;

    return 0;
}