Last updated on March 7th, 2025 at 07:22 pm

Here, we see a Sort Colors LeetCode Solution. This Leetcode problem is solved using different approaches in many programming languages, such as C++, Java, JavaScript, Python, etc.

List of all LeetCode Solution

Topics

Array, Sort, Two-Pointers

Companies

Facebook, Microsoft, Pocketgems

Level of Question

Medium

Sort Colors LeetCode Solution

1. Problem Statement

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]

2. Coding Pattern Used in Solution

The coding pattern used in the Java code is Two Pointers. The two pointers (p1 and p2) are used to segregate the 0s and 2s while iterating through the array. The JavaScript and Python codes use a Counting/Counting Sort pattern, where the frequency of each number is counted, and the array is reconstructed based on the counts. The C++ code uses the Sorting pattern by directly calling the sort function.

3. Code Implementation in Different Languages

3.1 Sort Colors C++

class Solution {
public:
    void sortColors(vector<int>& nums) {
       sort(nums.begin(), nums.end());        
    }
};

3.2 Sort Colors Java

class Solution {
    public void sortColors(int[] nums) {
    int p1 = 0, p2 = nums.length - 1, index = 0;
    while (index <= p2) {
        if (nums[index] == 0) {
            nums[index] = nums[p1];
            nums[p1] = 0;
            p1++;
        }
        if (nums[index] == 2) {
            nums[index] = nums[p2];
            nums[p2] = 2;
            p2--;
            index--;
        }
        index++;        
    }
    }
}

3.3 Sort Colors JavaScript

var sortColors = function(nums) {
    let one=0, zero=0, two=0
    for(let elem of nums){
        if(elem == 0) zero++
        else if ( elem == 1) one ++
        else two ++
    }
    nums.length=0
    for(let i=0;i<zero;i++) nums.push(0)
    for(let i=0;i<one;i++) nums.push(1)
    for(let i=0;i<two;i++) nums.push(2)     
};

3.4 Sort Colors Python

class Solution(object):
    def sortColors(self, nums):
        c0 = c1 = c2 = 0
        for num in nums:
            if num == 0:
                c0 += 1
            elif num == 1:
                c1 += 1
            else:
                c2 += 1
        nums[:c0] = [0] * c0
        nums[c0:c0+c1] = [1] * c1
        nums[c0+c1:] = [2] * c2

4. Time and Space Complexity

	Time Complexity	Space Complexity
C++	O(n log n)	O(1)
Java	O(n)	O(1)
JavaScript	O(n)	O(n)
Python	O(n)	O(1)

• The Java solution is the most efficient in terms of both time and space complexity.
• The C++ solution is less efficient due to the use of a general-purpose sorting algorithm.
• The JavaScript and Python solutions are efficient in time but differ in space complexity due to the way the array is reconstructed.