401. Binary Watch

//The __builtin_popcount() function is a built-in function in GCC and Clang compilers that counts the number of set bits (bits with a value of 1) in an integer.


//C++ Ternary or Conditional Operator
Last Updated : 31 Jul, 2023
In C++, the ternary or conditional operator ( ? : ) is the shortest form of writing conditional statements. It can be used as an inline conditional statement in place of if-else to execute some conditional code.

Syntax of Ternary Operator ( ? : )
The syntax of the ternary (or conditional) operator is:

expression ? statement_1 : statement_2;

As the name suggests, the ternary operator works on three operands where

expression: Condition to be evaluated.
statement_1: Statement that will be executed if the expression evaluates to true.
statement_2: Code to be executed if the expression evaluates to false.
// image

The above statement of the ternary operator is equivalent to the if-else statement given below:

if ( condition ) {
    statement1;
}
else {
    statement2;
}
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class Solution {
public:
    vector<string> readBinaryWatch(int turnedOn) {
        vector<string> binClk;
        if(turnedOn > 8)
        {
            return {};
        }
        for(int i = 0; i <= 11; i++)
        {
            for(int j = 0; j <= 59; j++)
            {
                int countH = __builtin_popcount(i);
                int countM = __builtin_popcount(j);
                if(countH + countM == turnedOn)
                {
                    string time = to_string(i) + ":" + (j < 10 ? "0" : "") + to_string(j);
                    binClk.push_back(time);
                }
            }
        }
        return binClk;
    }
};