LeetCode之Sqrt(x)

Implement int sqrt(int x).

Compute and return the square root of x.

注意：越界问题

class Solution {
public:
    int sqrt(int x) {
        if(x<0) return -1;
        if(x==0||x==1)  return x;
        int start,end;
        long long mid;              //!!!!!!int may cause overflow
        start=1,end=x>>1;
        while(end>=start){
            mid=(start+end)>>1;
            if(mid*mid<=x && (mid+1)*(mid+1)>x)
                return mid;
            else if(mid*mid>x)
                end=mid-1;
            else
                start=mid+1;
         }//while
    }
};

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LeetCode之Sqrt(x)

原文：http://blog.csdn.net/smileteo/article/details/22657969