sort-colors.cpp

//Given an array nums with n objects colored red, white, or blue, sort them in-place so that objects of the same color are adjacent, with the colors in the order red, white, and blue.

//We will use the integers 0, 1, and 2 to represent the color red, white, and blue, respectively.

//You must solve this problem without using the library's sort function.
//Example 1:

//Input: nums = [2,0,2,1,1,0]
//Output: [0,0,1,1,2,2]
//Example 2:

//Input: nums = [2,0,1]
//Output: [0,1,2]


class Solution {
public:
    void sortColors(vector<int>& nums) {
         int second = nums.size()-1; 
         int zero=0;
        for (int i=0; i<=second; i++) {
                while (nums[i]==2 && i<second) swap(nums[i], nums[second--]);
                while (nums[i]==0 && i>zero) swap(nums[i], nums[zero++]);
            }
        
    }
};