LeetCode 476) Number Complement

LV. Easy 😎

https://leetcode.com/problems/number-complement/

Number Complement - LeetCode

 

문제

The complement of an integer is the integer you get when you flip all the 0's to 1's and all the 1's to 0's in its binary representation.

• For example, The integer 5 is "101" in binary and its complement is "010" which is the integer 2.

Given an integer num, return its complement.

 

Example 1:

Input: num = 5
Output: 2
Explanation: The binary representation of 5 is 101 (no leading zero bits), and its complement is 010. So you need to output 2.

Example 2:

Input: num = 1
Output: 0
Explanation: The binary representation of 1 is 1 (no leading zero bits), and its complement is 0. So you need to output 0.

 

Constraints:

• 1 <= num < 2^31

 

문제 해결법

num를 2로 나누면서 나머지가 1이면 패스, 0이면 2^이진수의 자릿수를 곱해 num의 complement를 구한다

 

10진수를 2진수로 변환하는 법이 궁금하다면 아래 링크 클릭!

https://developer-eun-diary.tistory.com/entry/%EB%B6%80%EB%8F%99-%EC%86%8C%EC%88%98%EC%A0%90%EA%B3%BC-%EA%B3%A0%EC%A0%95-%EC%86%8C%EC%88%98%EC%A0%90

부동 소수점과 고정 소수점

 

해결 코드

#include <iostream>
#include <cmath>

class Solution {
public:
	int findComplement(int num) {
		int i = 0;
		int complement = 0;

		// get binary value and get complement value
		while (num != 1) {
			if (num % 2 == 0)
				complement += pow(2, i);
			num = num / 2;
			i++;
		}
		return complement;
	}
};

int main() {
	Solution sol;
	std::cout << sol.findComplement(1) << std::endl;
}