201. Bitwise AND of Numbers Range

https://leetcode.com/problems/bitwise-and-of-numbers-range/

1. Use Bitwise AND and check binary expression with only 1 bit:

//12 ms    6.1 MB
class Solution {
public:
    int rangeBitwiseAnd(int m, int n) {
        if(m==0)
            return 0;
        if(m==n)
            return m;
        int result = 2147483647;
        int curr;
        for(int i = 0; i <= 30; i++){
            curr = (1 << i);
            if((curr >= m) && (curr <= n)){
                result = curr;
                break;
            }
        }
        while(m <= n){
            result = result & m;
            if(result == 0){
                return result;
            }
            if(m == 2147483647)
                break;
            else
                m++;
        }
        return result;
    }
};