Sqrt(x)

Implement int sqrt(int x). 

    int sqrt(int x) {
        if (x < 0) return -1;
        int start = 0;
        int end = x;
        if (x == 0 || x == 1) return x;
        while (start <= end) {
                int mid = start + (end - start) / 2;
                if ((mid + 1) > x / (mid + 1) && (mid <= x / mid) ) {
                    return mid;
                } else if (mid < x / mid) {
                    start = mid + 1;
                } else {
                    end = mid - 1;
                }
        }
        return -1;
    }

Implement doublesqrt(double x)

public double sqrt(double x) {
	if (x < 0) return -1;
	double left  = 0;
	double right = (x < 1) ? 1 : x;
	double maxDiff = 0.000001;
	do {
		double mid = left + (right - left) / 2;
		if (Math.abs(x - mid * mid) <= maxDiff) {
			return mid;
		} else if (x - mid * mid < 0) {
			right = mid;
		} else {
			left = mid;
		}
	} while (true);
}

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