Day4 : 30 Day LeetCode may challenges

Number_Complement.cpp

//overcome runtime error by not doing n=n*2 operation causing overflow
class Solution {
public:
    int findComplement(int num) {
        /*
        5/2 = 2 and 5%2 = 1
        2/2 = 1 and 2%2 = 0
        1/2 = 0 and 1%2 = 1
        */
        /*int sum = 0;
        int l = 1;
        while(num != 0){
            if(num%2==0){
                sum+=l;
            }
            l = l*2;
            num = num/2;
        }
        return sum;
        */
        /*
        long long n = 1;
        while((int)n<=num){
            n = n*2;
        }
        return (int)(n-num-1);
        */
        int i;
        //if (num == 0)
            //return 1;
        for(i = 1; i<=31; i++){
            if(num == pow(2,i))
                return num-1;
            else if(num < pow(2,i))
                break;
        }
        return (pow(2,i)-1-num);
    }
};

problem_statement4.txt

Given a positive integer, output its complement number. The complement strategy is to flip the bits of its binary representation.

Example 1:

Input: 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: 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.
Note:

i . The given integer is guaranteed to fit within the range of a 32-bit signed integer.
ii. You could assume no leading zero bit in the integer’s binary representation.
iii.This question is the same as 1009: https://leetcode.com/problems/complement-of-base-10-integer/