In this post, we are going to solve the 75. Sort Colors problem of Leetcode. This problem 75. Sort Colors is a Leetcode medium level problem. Let’s see code, 75. Sort Colors – Leetcode Solution.

Problem

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]

Constraints

• n == nums.length
• 1 <= n <= 300
• nums[i] is either 0, 1, or 2.

Now, let’s see the code of 75. Sort Colors – Leetcode Solution.

Sort Colors – Leetcode Solution

75. Sort Colors – Solution in Java

class Solution {
    public void swap(int[] nums, int i, int j){
        int temp = nums[i];
        nums[i] = nums[j];
        nums[j] = temp;
    }
    public void sortColors(int[] nums) {
        int i=0,j=0,k=nums.length-1;
        while(i <= k){
            if(nums[i] == 0){
                swap(nums,i,j);
                i++;
                j++;
            }else if(nums[i] == 1){
                i++;
            }else if(nums[i] == 2){
                swap(nums,i,k);
                k--;
            }
        }
    }
}

75. Sort Colors – Solution in C++

class Solution {
public:
    void sortColors(vector<int>& nums) {
        int n = nums.size();
        int i = 0,j = 0,k = n-1;
        
        while(i<=k)
        {
            if(nums[i] == 0)
            {
                swap(nums[i++],nums[j++]);
            }
            else if(nums[i] == 1)
            {
                i++;
            }
            else if(nums[i] == 2)
            {
                swap(nums[i],nums[k]);
                k--;
            }

        }
    }
};

75. Sort Colors – Solution in Python

class Solution(object):
    def sortColors(self, nums):
        n=len(nums)
        zero,one,two=0,0,n-1
        while one<=two:
            if nums[one]==1:
                one+=1
            elif nums[one]==2:
                nums[one],nums[two]=nums[two],nums[one]
                two-=1

            else:
                nums[zero],nums[one]=nums[one],nums[zero]
                zero+=1
                one+=1
     

Note: This problem 75. Sort Colors is generated by Leetcode but the solution is provided by CodingBroz. This tutorial is only for Educational and Learning purpose.