2021-12-27 Daily-Challenge

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

December LeetCoding Challenge 27

Description

Number Complement

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/

Solution

class Solution {
public:
  int findComplement(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
// 149/149 cases passed (0 ms)
// Your runtime beats 100 % of cpp submissions
// Your memory usage beats 40.00 % of cpp submissions (6 MB)
Algorithm