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476. Number Complement

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

  • 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;
    }
}

  • 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;
    }
};

  • class Solution:
    def findComplement(self, num: int) -> int:
        return num ^ (2 ** (len(bin(num)[2:])) - 1)


  • 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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