[LeetCode] Problem 69 - Sqrt(x)

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Implement int sqrt(int x).

Compute and return the square root of x, where x is guaranteed to be a non-negative integer.

Since the return type is an integer, the decimal digits are truncated and only the integer part of the result is returned.

Example

No.1

Input: 4

Output: 2

No.2

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.

Code

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public int mySqrt(int x) {
    if (x == 0)
        return 0;

    int start = 1;
    int end = x;

    while (true) {
        int mid = start + (end - start) / 2;
        
        if (mid > x / mid)
            end = mid - 1;
        else {
            if ((mid + 1) > x / (mid + 1))
                return mid;
            
            start = mid + 1;
        }
    }
}