lintcode:x的平方根

x的平方根

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lintcode 题目链接

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class Solution {public:    /**     * @param x: An integer     * @return: The sqrt of x     */    int binary_search(long  l,long  r, long &x){        while(l<=r)        {            long mid=(l+r)>>1;            long long ans1=mid*mid;            long long ans2=(mid+1)*(mid+1);            if(ans1>x)                r=mid-1;            else if(ans1<x && ans2<=x)                 l=mid+1;            else if(ans1<=x &&ans2>x)                return mid;        }        return 0;    }    int sqrt(int x) {        // write your code here        long r=x;        if(r>3) r>>1;        return binary_search(1,r,r);    }};