1009. Complement of Base 10 Integer

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 n, return its complement.

 

Example 1:

Input: n = 5
Output: 2
Explanation: 5 is "101" in binary, with complement "010" in binary, which is 2 in base-10.

Example 2:

Input: n = 7
Output: 0
Explanation: 7 is "111" in binary, with complement "000" in binary, which is 0 in base-10.

Example 3:

Input: n = 10
Output: 5
Explanation: 10 is "1010" in binary, with complement "0101" in binary, which is 5 in base-10.

 

Constraints:

  • 0 <= n < 109

 

Note: This question is the same as 476: https://leetcode.com/problems/number-complement/

Solutions

Solution 1

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

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

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

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