D2 排序

https://www.nowcoder.com/practice/2baf799ea0594abd974d37139de27896?tpId=117&rp=1&ru=%2Fexam%2Fcompany&qru=%2Fexam%2Fcompany&sourceUrl=%2Fexam%2Fcompany&difficulty=&judgeStatus=&tags=&title=&gioEnter=menu

要点：

1. 归并排序 和 快速排序的实现

代码：

#include <iostream>
#include <vector>

using namespace std;
//快排
void quick_sort(vector<int>& nums, int left, int right) {
    if (left < right) {
        int low = left;
        int high = right;
        int x = nums[left];
        while (low < high) {
            while (low < high && nums[high] >= x) high--;
            if (low < high) nums[low++] = nums[high];
            while (low < high && nums[low] <= x) low++;
            if (low < high) nums[high--] = nums[low];
        }
        nums[low] = x;
        quick_sort(nums, left, low - 1);
        quick_sort(nums, low + 1, right);
    }
}

void merge(vector<int>& nums, int left, int mid, int right) {
    vector<int> tmp(right - left + 1);
    int k = 0;
    int i = left;
    int j = mid + 1;
    while (i <= mid && j <= right) {
        if (nums[i] < nums[j]) {
            tmp[k++] = nums[i++];
        }
        else {
            tmp[k++] = nums[j++];
        }
    }
    while (i <= mid) {
        tmp[k++] = nums[i++];
    }
    while (j <= right) {
        tmp[k++] = nums[j++];
    }
    for (int i = 0; i < tmp.size(); i++) {
        nums[left + i] = tmp[i];
    }
}

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

void print_vec(vector<int>& nums) {
    int len = nums.size();
    for (int i = 0; i < len; i++) {
        if (i == len - 1) {
            cout << nums[i] << endl;
        }
        else {
            cout << nums[i] << ' ';
        }
    }
}

int main() {
    vector<int> nums;
    int n;
    while (cin >> n) {
        nums.push_back(n);
        if (getchar() == '\n') {
            break;
        }
    }
    print_vec(nums);
    quick_sort(nums,0,nums.size()-1);
    print_vec(nums);
    return 0;
}