回溯法解决01背包问题

原文参看：http://blog.csdn.net/ljmingcom304/article/details/50314839

package com.alo.offer;import java.util.Arrays;import java.util.Collections;public class Recall {private Goods goods[] ;private int totalWeight;private int currentWeight;private int n;private int bestValue;private int currentValue;public Recall(Goods[] goods, int totalWeight, int n) {super();this.goods = goods;this.totalWeight = totalWeight;this.n = n;Arrays.sort(goods,Collections.reverseOrder());}public int solve(int i) {if(i>=n) {bestValue=currentValue;return bestValue;}if(currentWeight+goods[i].getWeight()<=totalWeight) {currentWeight+=goods[i].getWeight();currentValue+=goods[i].getValue();bestValue=solve(i+1);currentWeight-=goods[i].getWeight();currentValue-=goods[i].getValue();}if(currentValue+getSurplusValue(i+1)>bestValue) {bestValue=solve(i+1);}return bestValue;}private int getSurplusValue(int i) {// TODO Auto-generated method stubint surplusValue=0;for(int j=i;j<n;j++) {surplusValue+=goods[j].getValue();}return surplusValue;}public static void main(String[] args) {    Goods[] bags = new Goods[] { new Goods(2, 13),              new Goods(1, 10), new Goods(3, 24), new Goods(2, 15),              new Goods(4, 28), new Goods(5, 33), new Goods(3, 20),              new Goods(1, 8) };      int totalWeight = 12;      Recall problem = new Recall(bags, totalWeight,bags.length);        System.out.println(problem.solve(0)); }}