401. Binary Watch

/**
 * Problem: LeetCode 401 - Binary Watch
 * Difficulty: Easy
 * Language: Java
 * Author: CodeByTushu
 */
import java.util.ArrayList;
import java.util.List;

class Solution {
    public List<String> readBinaryWatch(int turnedOn) {
        List<String> result = new ArrayList<>();
        if (turnedOn < 0 || turnedOn > 8) {
            return result;
        }

        for (int h = 0; h < 12; h++) {
            for (int m = 0; m < 60; m++) {
                if (Integer.bitCount(h) + Integer.bitCount(m) == turnedOn) {
                    result.add(String.format("%d:%02d", h, m));
                }
            }
        }

        return result;
    }
}

"""
Problem: LeetCode 401 - Binary Watch
Difficulty: Easy
Language: Python
Author: CodeByTushu
"""
from typing import List

class Solution:
    def readBinaryWatch(self, turnedOn: int) -> List[str]:
        if turnedOn < 0 or turnedOn > 8:
            return []

        result = []
        for h in range(12):
            for m in range(60):
                if (bin(h).count('1') + bin(m).count('1')) == turnedOn:
                    result.append(f"{h}:{m:02d}")

        return result

/**
 * Problem: LeetCode 401 - Binary Watch
 * Difficulty: Easy
 * Language: C++
 * Author: CodeByTushu
 */
#include <vector>
#include <string>

using namespace std;

class Solution {
public:
    vector<string> readBinaryWatch(int turnedOn) {
        vector<string> result;
        if (turnedOn < 0 || turnedOn > 8) {
            return result;
        }

        for (int h = 0; h < 12; h++) {
            for (int m = 0; m < 60; m++) {
                if (__builtin_popcount(h) + __builtin_popcount(m) == turnedOn) {
                    string time = to_string(h) + ":" + (m < 10 ? "0" : "") + to_string(m);
                    result.push_back(time);
                }
            }
        }

        return result;
    }
};

/**
 * Problem: LeetCode 401 - Binary Watch
 * Difficulty: Easy
 * Language: JavaScript
 * Author: CodeByTushu
 */
/**
 * @param {number} turnedOn
 * @return {string[]}
 */
var readBinaryWatch = function(turnedOn) {
    if (turnedOn < 0 || turnedOn > 8) {
        return [];
    }

    const result = [];
    const countBits = (n) => {
        let count = 0;
        while (n > 0) {
            count += n & 1;
            n >>= 1;
        }
        return count;
    };

    for (let h = 0; h < 12; h++) {
        for (let m = 0; m < 60; m++) {
            if (countBits(h) + countBits(m) === turnedOn) {
                result.push(`${h}:${m < 10 ? '0' : ''}${m}`);
            }
        }
    }

    return result;
};