归并排序的c++实现

归并排序是一种基于分治策略的高效排序算法。它的基本思想是将数组不断二分，然后对每一半进行排序，最后合并两个有序部分。以下是C++实现归并排序的一个简单版本：

#include <vector>
using namespace std;

void merge(vector<int>& nums, int left, int mid, int right) {
    int n1 = mid - left + 1;
    int n2 = right - mid;
    
    vector<int> L(n1), R(n2);
    for (int i = 0; i < n1; i++)
        L[i] = nums[left + i];
    for (int j = 0; j < n2; j++)
        R[j] = nums[mid + 1 + j];

    int i = 0, j = 0, k = left;
    while (i < n1 && j < n2) {
        if (L[i] <= R[j])
            nums[k++] = L[i++];
        else
            nums[k++] = R[j++];
    }

    // 将剩余未处理的部分直接复制到结果数组
    while (i < n1)
        nums[k++] = L[i++];
    while (j < n2)
        nums[k++] = R[j++];
}

void mergeSort(vector<int>& nums, int left, int right) {
    if (left < right) {
        int mid = left + (right - left) / 2;
        mergeSort(nums, left, mid);
        mergeSort(nums, mid + 1, right);
        merge(nums, left, mid, right);
    }
}

// 主函数示例，用于测试归并排序
int main() {
    vector<int> nums = {4, 1, 3, 2, 6, 5};
    int size = nums.size();
    mergeSort(nums, 0, size - 1);
    for (int num : nums)
        cout << num << " ";
    return 0;
}