Easy-5

leetcode  476. Number Complement

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

Note:

1. The given integer is guaranteed to fit within the range of a 32-bit signed integer.
2. You could assume no leading zero bit in the integer’s binary representation.

Example 1:

Input: 5Output: 2Explanation: 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: 1Output: 0Explanation: The binary representation of 1 is 1 (no leading zero bits), and its complement is 0. So you need to output 0.

AC:

int findComplement(int num) {
    int k=num;
    int i=0;int sum=1;
    while(num>0){
        num=num>>1;
        i++;
    }
    for(int j=0;j<i;j++)
    {
        sum*=2;
    }
    return sum-1-k;
}

tips： >>右移一位，注意循环变量。