NYOJ之题目1058部分和问题

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简单搜索+剪枝

因为考虑到可能会有多个解，所以是将中间过程保存最后才一起打印出来的

AC代码：

  1: 
  2: import java.util.ArrayList;
  3: import java.util.List;
  4: import java.util.Scanner;
  5: 
  6: public class Main {
  7: 
  8: 	public static void main(String[] args) {
  9: 		
 10: 		Scanner sc=new Scanner(System.in);
 11: 		
 12: 		while(sc.hasNextInt()){
 13: 			
 14: 			int n=sc.nextInt();
 15: 			int k=sc.nextInt();
 16: 			
 17: 			int x[]=new int[n];
 18: 			for(int i=0;i<x.length;i++) x[i]=sc.nextInt();
 19: 			
 20: 			ans=new StringBuilder();
 21: 			dfs(x,0,k,new ArrayList<Integer>());
 22: 
 23: 			System.out.println(ans.length()==0?"NO":ans);
 24: 		}
 25: 		
 26: 	}
 27: 	
 28: 	private static StringBuilder ans;
 29: 	
 30: 	public static void dfs(int x[],int i,int k,List<Integer> trackStack){
 31: 		if(k==0){
 32: 			if(ans.length()==0) ans.append("YES
");
 33: 			for(int j=0;j<trackStack.size();j++) ans.append(trackStack.get(j)).append(" ");
 34: 			ans.append("
");
 35: 			return;
 36: 		} else if(i==x.length || k<0) return;
 37: 		
 38: 		trackStack.add(x[i]);
 39: 		dfs(x,i+1,k-x[i],trackStack);
 40: 		trackStack.remove(trackStack.size()-1);
 41: 		
 42: 		dfs(x,i+1,k,trackStack);
 43: 	}
 44: 	
 45: }

题目来源： http://acm.nyist.net/JudgeOnline/problem.php?pid=1058