# 401. Binary Watch(Solution || Leetcode easy || Java)

A binary watch has 4 LEDs on the top to represent the hours (0–11), and 6 LEDs on the bottom to represent the minutes (0–59). Each LED represents a zero or one, with the least significant bit on the right.

• For example, the below binary watch reads `"4:51"`.

Given an integer `turnedOn` which represents the number of LEDs that are currently on (ignoring the PM), return all possible times the watch could represent. You may return the answer in .

The hour must not contain a leading zero.

• For example, `"01:00"` is not valid. It should be `"1:00"`.

The minute must be consist of two digits and may contain a leading zero.

• For example, `"10:2"` is not valid. It should be `"10:02"`.

`Input: turnedOn = 1Output: ["0:01","0:02","0:04","0:08","0:16","0:32","1:00","2:00","4:00","8:00"]`

`Input: turnedOn = 9Output: []`

• `0 <= turnedOn <= 10`

# SOLUTION:

`class Solution {    public List<String> readBinaryWatch(int turnedOn) {//Create a list of string to store answers        List<String> ans = new ArrayList<>();//Start running loop to check for the hours        for(int hour = 0; hour < 12; hour++){//Start running loop to check the number of bits in minutes            for(int min = 0; min < 60; min++){//If the number of bits of hour and minute is equal to turnedOn then//add that time in our list                if(Integer.bitCount(hour) + Integer.bitCount(min) == turnedOn){                    String newTime = hour + ":";//If min is a single digit number, let say is 4 then, add a 0 before it                if(min < 10){                    newTime += 0;                }                                newTime += min;//add that time in our ans.                ans.add(newTime);                }                           }        }        return ans;    }}`

Runtime10 ms

Beats

77.83%

Memory41.1 MB

Beats

93.10%

Thank you for reading. If you have any queries then, please let me know in the comment section. I will surely be responsive toward it.

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