2022-01-04 Daily-Challenge

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Today I have done leetcode's January LeetCoding Challenge with cpp.

January LeetCoding Challenge 4

Description

Complement of Base 10 Integer

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 < 10^9

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

Solution

class Solution {
public:
  int bitwiseComplement(int n) {
    if(n > INT_MAX / 2) return INT_MAX ^ n;
    int bit = 1;
    while(bit <= n) {
      bit <<= 1;
    }
    return (bit - 1 | 1) ^ n;
  }
};

// Accepted
// 128/128 cases passed (0 ms)
// Your runtime beats 100 % of cpp submissions
// Your memory usage beats 75.27 % of cpp submissions (5.9 MB)
Algorithm