69. Sqrt(x)

Descr

class Solution {public:    int mySqrt(int x) {        if(x==0)return 0;int mid;int start=1,end=min(x/2,46340);while(start<end){mid=(start+end)/2;if(x/mid>=mid x/(mid+1)<mid+1)return mid;if(x/mid < mid)end = mid;if(x/(mid+1)>=mid+1)start=mid+1;}return start;    }};

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Implement int sqrt(int x).

Compute and return the square root of x.

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Seen this question in a real interview before?   

Yes

 

计算并返回x的平方根

使用for循环当然可以，但是二分法可以快速的解决

代码：

class Solution {public:    int mySqrt(int x) {        if(x==0)return 0;int mid;int start=1,end=min(x/2,46340);while(start<end){mid=(start+end)/2;if(x/mid>=mid x/(mid+1)<mid+1)return mid;if(x/mid < mid)end = mid;if(x/(mid+1)>=mid+1)start=mid+1;}return start;    }};