1356. Sort Integers by The Number of 1 Bits

/**
 * Problem: LeetCode 1356 - Sort Integers by The Number of 1 Bits
 * Difficulty: Easy
 * Language: Java
 * Author: CodeByTushu
 */
import java.util.Arrays;

class Solution {
    public int[] sortByBits(int[] arr) {
        // Since arr[i] <= 10000, we can encode the bit count into the number:
        // encoded = bitCount * 10001 + originalValue
        for (int i = 0; i < arr.length; i++) {
            arr[i] += Integer.bitCount(arr[i]) * 10001;
        }

        // Sort the primitive array directly in-place
        Arrays.sort(arr);

        // Decode the original value
        for (int i = 0; i < arr.length; i++) {
            arr[i] %= 10001;
        }

        return arr;
    }
}

"""
Problem: LeetCode 1356 - Sort Integers by The Number of 1 Bits
Difficulty: Easy
Language: Python
Author: CodeByTushu
"""
from typing import List

class Solution:
    def sortByBits(self, arr: List[int]) -> List[int]:
        return sorted(arr, key=lambda x: (x.bit_count(), x))

/**
 * Problem: LeetCode 1356 - Sort Integers by The Number of 1 Bits
 * Difficulty: Easy
 * Language: C++
 * Author: CodeByTushu
 */
#include <vector>
#include <algorithm>

using namespace std;

class Solution {
public:
    vector<int> sortByBits(vector<int>& arr) {
        sort(arr.begin(), arr.end(), [](int a, int b) {
            int countA = __builtin_popcount(a);
            int countB = __builtin_popcount(b);
            if (countA != countB) {
                return countA < countB;
            }
            return a < b;
        });
        return arr;
    }
};

/**
 * Problem: LeetCode 1356 - Sort Integers by The Number of 1 Bits
 * Difficulty: Easy
 * Language: JavaScript
 * Author: CodeByTushu
 */
/**
 * @param {number[]} arr
 * @return {number[]}
 */
var sortByBits = function(arr) {
    function countBits(n) {
        let count = 0;
        while (n > 0) {
            n &= (n - 1);
            count++;
        }
        return count;
    }

    return arr.sort((a, b) => {
        const bitsA = countBits(a);
        const bitsB = countBits(b);
        if (bitsA !== bitsB) {
            return bitsA - bitsB;
        }
        return a - b;
    });
};