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.

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

[思路]

等价于 求 m 与 n 二进制编码中 同为1的前缀.

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