Bitwise AND of Numbers Range

 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.

Credits:

Special thanks to @amrsaqr for adding this problem and creating all test cases.
解析：
多个连续的数相与的结果就是这些数左边相同的那些位，也即是最大数与最小数左边相同的位

代码：

class Solution {
public:
int rangeBitwiseAnd(int m, int n) {
unsigned int mask=INT_MAX;
while(m!=n)
{
mask<<=1;
m&=mask;
n&=mask;

}
int ans=mask&n;

return ans;
}
};