leetcode[69]Sqrt(x)

class Solution {
public:
int sqrt(int x)
{
    long long left=0,right=x/2+1;
    while(left<=right)
    {
        long long mid=(left+right)/2;
        if(mid*mid<=x&&(mid+1)*(mid+1)>x)return (int)mid;
        else if(mid*mid<x) left=mid+1;
        else right=mid-1;
    }
}
/**
int sqrt(int x)
{
    if(x==0)return 0;
    double pre=0,cur=1;
    while(abs(cur-pre)>0.00001)
    {
        pre=cur;
        cur=(pre+x/pre)/2;
    }
    return int(cur);
}
*/
};