n_sqrt.java

static double sqrt(double target) {
        double l_min = 0, l_max = 1000, cur = 100;
        double err = 0.000000000000001;
        while ((l_max - l_min) > err) {
            if (cur * cur > target) {
                l_max = cur;
                cur = (cur + l_min) / 2;
            } else {
                l_min = cur;
                cur = (l_max + cur) / 2;
            }
        }
        return cur;
    }