Sqrt(x)

Desicription

Implement int sqrt(int x).

Compute and return the square root of x.

x is guaranteed to be a non-negative integer.

Example 1:

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Input: 4
Output: 2

Example 2:

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Input: 8
Output: 2
Explanation: The square root of 8 is 2.82842..., and since we want to return an integer, the decimal part will be truncated.

Solution

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class Solution {
public:
    int mySqrt(int x) {
        long r = x;
        while (r*r > x)
            r = (r + x/r) / 2;
        return r;
    }
};