【leetcode】 Bitwise AND of Numbers Range

From： https://leetcode.com/problems/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.

Solution 1：

public class Solution {    public int rangeBitwiseAnd(int m, int n) {        if( m>n || m<=0 || n<=0) return 0;        if(m == n)  return m;        if(m == n-1)    return m&n;        int mid = (m+n)/2;        return  mid & rangeBitwiseAnd(m,mid-1) & rangeBitwiseAnd(mid+1,n);     }}

Solution 2：

class Solution {public:    int rangeBitwiseAnd(int m, int n) {        if(m == 0) return 0;        int moveFactor = 1;        while(m != n){            m >>= 1;            n >>= 1;            moveFactor <<= 1;        }        return m * moveFactor;    }};