[2016.4][京东暑期实习笔试]生日礼物

package bupt.syh;

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {

	private static Envelope card;
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		List<Envelope> list = new ArrayList<Envelope>();
		while (in.hasNext()) {
			list.clear();
			int enveNum = in.nextInt();
			long cardX = in.nextLong();
			long cardY = in.nextLong();
			card = new Envelope(cardX, cardY);
			while (enveNum-- > 0) {
				long elX = in.nextLong();
				long elY = in.nextLong();
				Envelope envelop = new Envelope(elX, elY);
				list.add(envelop);
			}
			List<Integer> indexList = new ArrayList<Integer>(); // 信封的序号的序列
			List<List<Integer>> rstList = new ArrayList<List<Integer>>();  // 所有序列的集合
			helper(rstList, indexList, list);
			
			int maxEnvelopeNum = Integer.MIN_VALUE;
			List<Integer> longest = null;
			for (List<Integer> each : rstList) {
				if (maxEnvelopeNum < each.size()) {
					maxEnvelopeNum = each.size();
					longest = each;
				}
			}
			
			// print
			System.out.println(maxEnvelopeNum);
			StringBuilder builder = new StringBuilder();
			for (int i = 0; i < longest.size(); i++) {
				builder.append(longest.get(i) + 1 + " ");
			}
			System.out.println(builder.toString().trim());
		}
	}
	
	// 搜索
	public static void helper(List<List<Integer>> rstList, List<Integer> indexList, List<Envelope> enveLopeList) {
		Envelope outestEnvelope = null; // 当前最外层的信封
		if (indexList.isEmpty()) {
			outestEnvelope = card;
		} else {
			outestEnvelope = enveLopeList.get(indexList.get(indexList.size() - 1));
		}
		
		for (int i = 0; i < enveLopeList.size(); i++) {
			Envelope nextEnvelope = enveLopeList.get(i);
			if (outestEnvelope.canInto(nextEnvelope)) {
				indexList.add(i);
				helper(rstList, indexList, enveLopeList);
				indexList.remove(indexList.size() - 1); //取出来
			}
		}
		rstList.add(new ArrayList<Integer>(indexList));
	}
	
	static class Envelope {
		public long x;
		public long y;
		
		public Envelope(long x, long y) {
			super();
			this.x = x;
			this.y = y;
		}
		
		// 可不可以放的进
		public boolean canInto(Envelope el) {
			if (x < el.x && y < el.y) {
				return true;
			} else {
				return false;
			}
		}
		
	}
	
	
}