Sort Colors

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

Here, we will use the integer 0, 1, and 2 to represent the color red, white, and blue respectively.

 Notice

You are not supposed to use the library's sort function for this problem. 
You should do it in-place (sort numbers in the original array).

 

Runtime: 82ms

class Solution{
public:
    /**
     * @param nums: A list of integer which is 0, 1 or 2 
     * @return: nothing
     */    
    void sortColors(vector<int> &nums) {
        // write your code here
        if (nums.size() < 2) return;
        
        int left = 0, right = nums.size() - 1;
        int index = 0;
        while (index <= right) {
            if (nums[index] == 0)
                swap(nums[index++], nums[left++]);
            else if (nums[index] == 2)
                swap(nums[index], nums[right--]);
            else
                index++;
        }
    }
};