Bitwise AND of Numbers Range

Source

• leetcode: Bitwise AND of Numbers Range

Given a range [m, n] where 0 <= m <= n <= 2147483647, return the bitwise
AND of all numbers in this range, inclusive.

For example, given the range [5, 7], you should return 4.

Java

public class Solution {
    public int rangeBitwiseAnd(int m, int n) {
        int result=1;
        while(m!=n){
            m>>=1;
            n>>=1;
            result <<=1;
        }
        return m*result;
    }
}

/*
The idea is very simple:

last bit of (odd number & even number) is 0.
when m != n, There is at least an odd number and an even number, so the last bit position result is 0.
Move m and n rigth a position.
Keep doing step 1,2,3 until m equal to n, use a factor to record the iteration time.
https://leetcode.com/discuss/32115/bit-operation-solution-java
*/