二分求x的平方根保留4位小数

import java.text.DecimalFormat;

class Solution {

    public static void main(String[] args) {
        System.out.println(sqrt(8));
    }

    public static double sqrt(double x) {
        double left = 0, right = x;
        double mid = left + (right - left) / 2;
        while (Math.abs(x - mid * mid) > 0.00001) {
            mid = left + (right - left) / 2;
            if (mid * mid == x) {
                return mid;
            } else if (mid * mid < x) {
                left = mid;
            } else {
                right = mid;
            }
        }
        DecimalFormat df = new DecimalFormat("#.0000");
        return Double.parseDouble(df.format(mid));
    }
}

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