75. Sort Colors

写个快排挺好的

class Solution {
public:
    void quicksort(vector<int>& nums,int i,int j){
    if(i>=j)return;
    int index=i;
    int end=j;
    int key=nums[index];
    while(i<j){
        while(nums[j]>key&&i<j)--j;
        while(nums[i]<=key&&i<j)++i;
        swap(nums[i],nums[j]);
        if(i<j)--j;
    }
    swap(nums[index],nums[j]);
    quicksort(nums,index,j-1);
    quicksort(nums,j+1,end);
}
    void sortColors(vector<int>& nums) {
        quicksort(nums,0,nums.size()-1);
    }
};