Sqrt(x)解题报告

</pre><pre name="code" class="cpp">int mySqrt(int x) {int e = 0;long long ret = 0;while((long long)(ret * ret) <= (long long)x){ret = (int)pow(2.0, e++);}int l = 0;int r = ret;while(l <= r){int mid = (l + r) >> 1;int sq = mid * mid;if(sq == x)return mid;else if(sq > x || sq < 0)r = mid - 1;else l = mid + 1;}return l - 1;    }