README_EN.md

476. Number Complement

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Description

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 < 231

 

Note: This question is the same as 1009: https://leetcode.com/problems/complement-of-base-10-integer/

Solutions

Python3

class Solution:
    def findComplement(self, num: int) -> int:
        ans = 0
        find = False
        for i in range(30, -1, -1):
            b = num & (1 << i)
            if not find and b == 0:
                continue
            find = True
            if b == 0:
                ans |= 1 << i
        return ans

Java

class Solution {
    public int findComplement(int num) {
        int ans = 0;
        boolean find = false;
        for (int i = 30; i >= 0; --i) {
            int b = num & (1 << i);
            if (!find && b == 0) {
                continue;
            }
            find = true;
            if (b == 0) {
                ans |= (1 << i);
            }
        }
        return ans;
    }
}

C++

class Solution {
public:
    int findComplement(int num) {
        int full = pow(2, int(log2(num)) + 1) - 1;
        return full ^ num;
    }
};

class Solution {
public:
    int findComplement(int num) {
        int ans = 0;
        bool find = false;
        for (int i = 30; i >= 0; --i)
        {
            int b = num & (1 << i);
            if (!find && b == 0) continue;
            find = true;
            if (b == 0) ans |= (1 << i);
        }
        return ans;
    }
};

Go

func findComplement(num int) int {
	ans := 0
	find := false
	for i := 30; i >= 0; i-- {
		b := num & (1 << i)
		if !find && b == 0 {
			continue
		}
		find = true
		if b == 0 {
			ans |= (1 << i)
		}
	}
	return ans
}

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