075_Sort Colors

    class Solution {
    public:
        void sortColors(int A[], int n) {
            int second=n-1, zero=0;
            for (int i=0; i<=second; i++) {
                while (A[i]==2 && i<second) swap(A[i], A[second--]);//the order is important!
                while (A[i]==0 && i>zero) swap(A[i], A[zero++]);
            }
        }
    };
    
class Solution {
public:
    void sortColors(vector<int>& nums) {
        int lo = 0, hi = nums.size() - 1;
        for (int i = 0; i <= hi;)
        {   
            if (nums[i]==0)
            {
                swap(nums[i], nums[lo]);
                lo++;
                i++;                 
            }
            else if(nums[i]==2)
            {
                swap(nums[i], nums[hi]);
                hi--;
            }
            else i++;
        }        
    }
};