3663939_ac_172ms_2724k.java

北大大牛代码 1240道题的原代码 超级权威

import java.util.*;

public class Main {
	private Scanner in;

	public static void main(String[] args) {
		new Main().run();
	}

	private double calc(String smeech) {
		if (smeech.indexOf('(') == -1) {
			return new Double(smeech);
		}
		double p = 0;
		double e1, e2;
		e1 = e2 = 0;
		int length = smeech.length();
		for (int i = 0; ; i++) {
			if (smeech.charAt(i) == ' ') {
				p = new Double(smeech.substring(1, i));
				int l, r;
				l = r = 0;
				if (smeech.charAt(i + 1) == '(') {
					for (int j = i + 1; ; j++) {
						if (smeech.charAt(j) == '(') {
							l++;
						}
						if (smeech.charAt(j) == ')') {
							r++;
						}
						if (l == r) {
							e1 = calc(smeech.substring(i + 1, j + 1));
							e2 = calc(smeech.substring(j + 2, length - 1));
							break;
						}
					}
				} else {
					for (int j = i + 1; ; j++) {
						if (smeech.charAt(j) == ' ') {
							e1 = new Double(smeech.substring(i + 1, j));
							e2 = calc(smeech.substring(j + 1, length - 1));
							break;
						}
					}
				}
				break;
			}
		}
		return p * (e1 + e2) + (1 - p) * (e1 - e2);
	}

	private void run() {
		in = new Scanner(System.in);
		String smeech;

		while (true) {
			smeech = in.nextLine();
			if ("()".equals(smeech)) {
				break;
			}
			System.out.printf("%.2f\n", calc(smeech));
		}
	}
}