化学方程式

原题链接
用java练练手。
遇到括号递归进行处理，就是传递引用比价麻烦，这里是传递了个一个数字的数组，以后想到优雅的做法在再补充。

import java.util.HashMap;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		sc.nextLine();
		for (int i = 0; i < n; i++) {
			String s = sc.nextLine();
			if (judge(s))
				System.out.println("Y");
			else
				System.out.println("N");
		}
		sc.close();
	}

	private static boolean judge(String s) {
		int idx = s.indexOf('=');
		HashMap<String, Integer> hm1 = work(s.substring(0, idx));
		HashMap<String, Integer> hm2 = work(s.substring(idx + 1, s.length()));
		return hm1.equals(hm2);
	}

	private static HashMap<String, Integer> work(String str) {
		HashMap<String, Integer> res = new HashMap<String, Integer>();
		String[] item = str.split("\\+");
		for (int i = 0; i < item.length; i++) {
			int j = 0;
			while (j < item[i].length() && Character.isDigit(item[i].charAt(j)))
				j++;
			int cnt = 1;
			if (j > 0) {
				cnt = Integer.parseInt(item[i].substring(0, j));
				item[i] = item[i].substring(j);
			}
			HashMap<String, Integer> hm = work_item(item[i], new int[] { 0 });
			for (String s : hm.keySet()) {
				if (res.containsKey(s))
					res.put(s, res.get(s) + hm.get(s) * cnt);
				else
					res.put(s, hm.get(s) * cnt);
			}
		}
		return res;
	}

	private static HashMap<String, Integer> work_item(String s, int[] num) {
		HashMap<String, Integer> res = new HashMap<String, Integer>();
		while (num[0] < s.length()) {
			switch (s.charAt(num[0])) {
			case '(':
				num[0]++;
				HashMap<String, Integer> hm = work_item(s, num);
				int cnt = 1;
				int x = num[0];
				while (num[0] < s.length() && Character.isDigit(s.charAt(num[0])))
					num[0]++;
				if (num[0] > x)
					cnt = Integer.parseInt(s.substring(x, num[0]));
				for (String t : hm.keySet()) {
					if (res.containsKey(t))
						res.put(t, res.get(t) + hm.get(t) * cnt);
					else
						res.put(t, hm.get(t) * cnt);
				}
				break;
			case ')':
				num[0]++;
				return res;
			default:
				int j = num[0] + 1;
				while (j < s.length() && Character.isLowerCase(s.charAt(j)))
					j++;
				String str = s.substring(num[0], j);
				int count = 1;
				int e = j;
				while (e < s.length() && Character.isDigit(s.charAt(e)))
					e++;
				if (e > j)
					count = Integer.parseInt(s.substring(j, e));
				num[0] = e;
				if (res.containsKey(str))
					res.put(str, res.get(str) + count);
				else
					res.put(str, count);
				break;
			}
		}
		return res;
	}

}