一。二叉树：
1.确定左右界
2.算mid
3.根据条件调整左右键
4.重复2-3
5根据条件返回mid
public int sqrt(int x) {
if (x == 0)
return 0;
int left = 1, right = Integer.MAX_VALUE;
while (true) {
int mid = left + (right - left)/2;
if (mid > x/mid) {
right = mid - 1;
} else {
if (mid + 1 > x/(mid + 1))
return mid;
left = mid + 1;
}
}
}
https://leetcode.com/problems/sqrtx/#/solutions
二：简写
r = x while r*r > x: r = (r + x/r) / 2 return r
long r = x;
while (r*r > x)
r = (r + x/r) /
2;
return (
int) r;
https://leetcode.com/problems/sqrtx/#/solutions
