201. 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.

Example 1:

Input: [5,7]
Output: 4

Example 2:

Input: [0,1]
Output: 0

int rangeBitwiseAnd(int m, int n) { // time: O(1); space: O(1)
    while (n > m) {
        n &= (n - 1);
    }
    return n;
}

int rangeBitwiseAnd(int m, int n) { // time: O(1); space: O(1)
    int i = 0;
    while (m != n) {
        m >>= 1;
        n >>= 1;
        ++i;
    }
    return m << i;
}