LeetCode "Bitwise AND of Numbers Range"

class Solution {
public:
    int rangeBitwiseAnd(int m, int n) {
        if (m == n) return m;
        int r = 0;
        int cnt = 0;
        while (m && m < n)
        {    
            cnt++;
            m >>= 1;
            n >>= 1;
        }
        if (m == n && m > 0)
            r = m << cnt;
        return r;
    }
};