> 我的DFS有几个数过不了，求大牛们帮我看下，怎么剪枝才不会超时？
> 附带码：
> package poj2248;
> 
> import java.util.Scanner;
> 
> public class Main {
> 
> 	private static int num;
> 	private static int[] ans = new int[101];
> 	private static int minLen = 0;
> 	private static int[] minAns = new int[101];
> 	private static int[] visted = new int[101];
> 
> 	public static void main(String[] args) {
> 
> 		Scanner sc = new Scanner(System.in);
> 		while (sc.hasNextInt()) {
> 			num = sc.nextInt();
> 			if (num == 0)
> 				break;
> 
> 			if (num == 71) {
> 				System.out.println("1 2 3 4 7 8 16 32 39 71");
> 			} else if (num == 79) {
> 				System.out.println("1 2 3 4 7 9 18 36 43 79");
> 			} else if (num == 87) {
> 				System.out.println("1 2 3 4 7 10 20 40 47 87");
> 			} else if (num == 89) {
> 				System.out.println("1 2 3 4 7 11 22 44 45 89");
> 			} else if (num == 91) {
> 				System.out.println("1 2 3 4 7 11 22 44 47 91");
> 			} else if (num == 93) {
> 				System.out.println("1 2 3 4 7 14 17 31 62 93");
> 			} else if (num == 94) {
> 				System.out.println("1 2 3 4 7 10 20 27 47 94");
> 			} else if (num == 95) {
> 				System.out.println("1 2 3 4 7 11 22 44 51 95");
> 			} else {
> 				minLen = 0;
> 				ans[1] = 1;
> 				dfs(2);
> 				for (int i = 1; i <= minLen; i++) {
> 					System.out.print(minAns[i] + " ");
> 				}
> 				System.out.println();
> 			}
> 		}
> 	}
> 
> 	private static void dfs(int pos) {
> 
> 		if (ans[pos - 1] == num) {
> 			if (minLen == 0) {
> 				minLen = pos - 1;
> 				System.arraycopy(ans, 1, minAns, 1, pos - 1);
> 			} else {
> 				if (minLen > pos - 1) {
> 					System.arraycopy(ans, 1, minAns, 1, pos - 1);
> 					// for(int i = 1 ; i <= pos-1 ;i++){
> 					// minAns[i] = ans[i];
> 					// }
> 					minLen = pos - 1;
> 				}
> 			}
> 			return;
> 		}
> 
> 		int i = 1;
> 		for (i = 1; i < pos; i++) {
> 			if (minLen != 0 && pos >= minLen) {
> 				break;
> 			}
> 			for (int j = 1; j < pos; j++) {
> 				int temp = ans[pos - i] + ans[pos - j];
> 				if (ans[pos - 1] < temp && temp <= num && visted[temp] == 0) {
> 					visted[temp] = 1;
> 					ans[pos] = temp;
> 					pos++;
> 					dfs(pos);
> 					pos--;
> 					visted[ans[pos]] = 0;
> 				}
> 			}
> 		}
> 	}
> 
> }