Leetcode | Sqrt(x)

Implement int sqrt(int x).

Compute and return the square root of x.

线性查找会TLE。用二分查找。注意溢出的处理。全部都改成long long.

class Solution {
public:
int sqrt(int x) {
if (x <= 1) return x;
long long l = 1, r = x / 2 + 1;

while (l <= r) {
long long m = (l + r) / 2;
long long v = m * m;
if (v == x) return m;
else if (v < x) {
l = m + 1;
} else {
r = m - 1;
}
}

return r;
}
};