LeetCode 201 Bitwise AND of Numbers Range (位运算)

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.

Credits:
Special thanks to @amrsaqr for adding this problem and creating all test cases.

题目链接：https://leetcode.com/problems/bitwise-and-of-numbers-range/

题目分析：1每乘一次2，相当于左移一位，这样会造成其非最高位都为0，与运算遇到0结果肯定为0，所以其实只要看n和m对应位的状态，同1则加，同0继续比较，若一个为1一个为0，则后面与的结果必定都是0

public class Solution {    public int rangeBitwiseAnd(int m, int n) {        int sta1 = 0, sta2 = 0, ans = 0;        for (int i = 31; i >= 0; i --) {            sta1 = ((1 << i) & m);            sta2 = ((1 << i) & n);            if ((sta1 & sta2) != 0) {                ans |= (1 << i);            }            else if (sta1 != 0 || sta2 != 0) {                return ans;            }        }        return ans;    }}