一.快速排序

#include <bits/stdc++.h>

using namespace std;
// 分区函数
int partition(std::vector<int>& arr, int low, int high) {
    int i = low;
    int j = high;
    int target = arr[i];
    while(i<j){
        while(i<j&&arr[j]>=target){
            j--;
        }
        if(i<j){
            swap(arr[i],arr[j]);
            i++;
        }
        while(i<j&&arr[i]<target){
            i++;
        }
        if(i<j){
            swap(arr[i],arr[j]);
            j--;
        }
    }
    return i;
}

// 快速排序函数
void quickSort(std::vector<int>& arr, int low, int high) {
    if(low<high){
        int part = partition(arr,low,high);
        quickSort(arr,low,part-1);
        quickSort(arr,part+1,high);
    }
}

int main() {
    std::vector<int> arr = {10, 7, 8, 9, 1, 5};
    int n = arr.size();
    quickSort(arr, 0, n - 1);
    
    std::cout << "Sorted array: ";
    for (int i = 0; i < n; ++i) {
        std::cout << arr[i] << " ";
    }
    std::cout << std::endl;
    
    return 0;
}

二.归并排序

#include <iostream>
#include <vector>

// 合并两个子数组
void merge(std::vector<int>& arr, int left, int mid, int right) {
    int n1 = mid - left + 1;
    int n2 = right - mid;
    // 创建临时数组
    std::vector<int> leftArr(n1), rightArr(n2);
    // 拷贝数据到临时数组
    for (int i = 0; i < n1; ++i)
        leftArr[i] = arr[left + i];
    for (int j = 0; j < n2; ++j)
        rightArr[j] = arr[mid + 1 + j];
    // 合并临时数组回到原数组
    int i = 0, j = 0, k = left;
    while (i < n1 && j < n2) {
        if (leftArr[i] <= rightArr[j]) {
            arr[k] = leftArr[i];
            ++i;
        } else {
            arr[k] = rightArr[j];
            ++j;
        }
        ++k;
    }
    // 拷贝剩余元素（如果有）
    while (i < n1) {
        arr[k] = leftArr[i];
        ++i;
        ++k;
    }
    while (j < n2) {
        arr[k] = rightArr[j];
        ++j;
        ++k;
    }
}

// 归并排序函数
void mergeSort(std::vector<int>& arr, int left, int right) {
    if (left < right) {
        int mid = left + (right - left) / 2;
        // 递归排序两个子数组
        mergeSort(arr, left, mid);
        mergeSort(arr, mid + 1, right);
        // 合并两个子数组
        merge(arr, left, mid, right);
    }
}

int main() {
    std::vector<int> arr = {12, 11, 13, 5, 6, 7};
    int arr_size = arr.size();
    std::cout << "Given array is \n";
    for (int i = 0; i < arr_size; i++)
        std::cout << arr[i] << " ";
    std::cout << std::endl;
    mergeSort(arr, 0, arr_size - 1);
    std::cout << "Sorted array is \n";
    for (int i = 0; i < arr_size; i++)
        std::cout << arr[i] << " ";
    std::cout << std::endl;
    return 0;
}

三.桶排序（基数排序）

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
class Solution {
public:
    void jishu(vector<int>& nums) {
        int n = nums.size();
        //如果数组元素个数小于 2，则返回 0
        if(n < 2)
        {
            return;
        }
        vector<int> buf(n);             //buf为临时顺组，用于存储每次排完序的数组
        int maxVal = *max_element(nums.begin(), nums.end());
        int time = maxBit(maxVal);      //计算出需要最高位数，即需要排多少次
        int dev = 1;
        //开始从低位到高位基数排序
        for(int i = 0; i < time; i++){
            vector<vector<int>> count(10);      //桶
            //统计每个桶中有多少个数
            for(int j = 0; j < n; j++){
                int digit = (nums[j] / dev) % 10;     //digit 为nums[j]的第i位数
                count[digit].emplace_back(nums[j]);
            }
            int index = n-1;

            for(int number = 9;number>=0;number--){
                while(count[number].size()>0){
                    nums[index] = count[number].back();
                    count[number].pop_back();
                    index--;
                }
            }
            dev *= 10;
        }
    }
    int maxBit(int maxVal){
        int p = 10;
        int d = 1;
        while(maxVal >= p){
            p *= 10;
            d++;
        }
        return d;
    }
};
int main() {
    std::vector<int> arr = {12, 11, 13, 5, 6, 7};
    int arr_size = arr.size();

    std::cout << "Given array is \n";
    for (int i = 0; i < arr_size; i++)
        std::cout << arr[i] << " ";
    std::cout << std::endl;
    Solution a;
    cout<<"jishu"<<endl;
    a.jishu(arr);

    std::cout << "Sorted array is \n";
    for (int i = 0; i < arr_size; i++)
        std::cout << arr[i] << " ";
    std::cout << std::endl;

    return 0;
}