LeetCode 069 Sqrt(x)

class Solution {
public:
int mySqrt(int x) {
long long begin=0;
long long end=x;
while(begin<=end){
long long mid=(begin+end)>>1;
if(mid*mid<=x&&x<(mid+1)*(mid+1))return mid;
else if(mid*mid<x)begin=mid+1;
else end=mid-1;
//cout<<begin<<" "<<end<<endl;
}
}
};