Sort Colors

Question: Given an array 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.

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

Note: You are not suppose to use the library’s sort function for this problem.

Example:

Input: [2,0,2,1,1,0]
Output: [0,0,1,1,2,2]

You may view the full question here.

Approach 1: In place sorting! Well here is an attempt —

//Approach 1:
//Runtime: 0ms
//Memory usage: 37.1MB
class Solution {
    public void sortColors(int[] nums) {
        int start = 0;
        int i = 0;
        int end = nums.length-1;
        int temp;
        while(i<=end){
            if(nums[i]==2){
                temp = nums[end];
                nums[end] = nums[i];
                nums[i] = temp;
                end--;
            } else if(nums[i]==1){
                i++;
            } else if(nums[i]==0){
                temp = nums[start];
                nums[start] = nums[i];
                nums[i] = temp;
                start++;
                i++;
            }
        }
    }
}

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Cheers & Chao!