常见排序算法C++实现

快速排序:

class Solution {
public:
    void quickSort(vector<int>& nums,int begin,int end) {
        if(begin>=end) {
            return ;
        }
        int poivt=nums[begin];
        int index=begin+1;
        int index2=end;
        int temp;
        while(index<=index2) {
            if(nums[index2]<poivt) {
                temp=nums[index];
                nums[index]=nums[index2];
                nums[index2]=temp;
                index++;
            } else {
                index2--;
            }
        }
        int swap_index=index-1;
        temp=nums[swap_index];
        nums[swap_index]=nums[begin];
        nums[begin]=temp;
        quickSort(nums,begin,swap_index-1);
        quickSort(nums,swap_index+1,end);
    }
    vector<int> sortArray(vector<int>& nums) {
        quickSort(nums,0,nums.size()-1);
        return nums;
    }
};

归并排序：

void recursive(vector<int>& vec,int start,int end) {
    if(start>=end) {
        return ;
    }
    int mid=(start+end)/2;
    recursive(vec,start,mid);
    recursive(vec,mid+1,end);
    vector<int> copy;
    int index1=start;
    int index2=mid+1;
    while(index1<=mid&&index2<=end) {
        if(vec[index1]<vec[index2]) {
            copy.push_back(vec[index1++]);
        } else {
            copy.push_back(vec[index2++]);
        }
    }
    while(index1<=mid) {
        copy.push_back(vec[index1++]);
    }
    while(index2<=end) {
        copy.push_back(vec[index2++]);
    }
    for (int i = start; i <= end; i++)
    {
        vec[i]=copy[i-start];
    }
}

void mergeSort(vector<int>& vec) {
    recursive(vec,0,vec.size()-1);
}