剑指offer题23

package jianzhioffer;import java.util.ArrayList;import java.util.Scanner;/** * 输入一颗二叉树和一个整数，打印出二叉树中结点值的和为输入整数的所有路径。 * 路径定义为从树的根结点开始往下一直到叶结点所经过的结点形成一条路径。 * *//**节点类public class TreeNode {    int val = 0;    TreeNode left = null;    TreeNode right = null;    public TreeNode(int val) {        this.val = val;    }}*/public class Solution23 {//运用递归，从根节点逐次向下遍历，当到达叶子结点且正好target为0时，加入队列；如果//如果节点值大于target，则没必要往下遍历，提前结束static ArrayList<ArrayList<Integer>> alllist = new ArrayList<ArrayList<Integer>>();static ArrayList<Integer> list = new ArrayList<Integer>();public static ArrayList<ArrayList<Integer>> FindPath(TreeNode root,int target) {if(root == null){return alllist;}list.add(root.val);target -= root.val;if(target == 0&& root.left == null && root.right == null){alllist.add(new ArrayList<Integer>(list));}FindPath(root.left,target);FindPath(root.right,target);list.remove(list.size()-1);return alllist;    }/*public static ArrayList<ArrayList<Integer>> FindPath(TreeNode root,int target) {ArrayList<ArrayList<Integer>> alllist = new ArrayList<>();ArrayList<Integer> list = new ArrayList<>();if(root == null){return alllist;}return find(root,target,alllist,list);}private static ArrayList<ArrayList<Integer>> find(TreeNode root,int target, ArrayList<ArrayList<Integer>> alllist,ArrayList<Integer> list) {if(root == null || root.val >target){if(target == 0 && root == null){alllist.add(list);}return alllist;}list.add(root.val);ArrayList<Integer> left_list = new ArrayList<>();left_list.addAll(list);ArrayList<Integer> right_list = new ArrayList<>();right_list.addAll(list);if(root.left == null && root.right == null){find(root.left,target-root.val,alllist,left_list);}else{find(root.left,target-root.val,alllist,left_list);find(root.right,target-root.val,alllist,right_list);}return alllist;}*/public static void main(String[] args) {Scanner sc = new Scanner(System.in);int n = sc.nextInt();  int target = sc.nextInt();  int[] arr = new int[n];for(int i = 0;i<n;i++){arr[i] = sc.nextInt();}TreeNode tree1 = new TreeNode(arr[0]);TreeNode tree2 = new TreeNode(arr[1]);TreeNode tree3 = new TreeNode(arr[2]);TreeNode tree4 = new TreeNode(arr[3]);TreeNode tree5 = new TreeNode(arr[4]);TreeNode tree6 = new TreeNode(arr[5]);TreeNode tree7 = new TreeNode(arr[6]);tree1.left = tree2;    tree1.right = tree3;    tree2.left = tree4;    tree2.right = tree5;    tree3.left = tree6;    tree3.right = tree7;        ArrayList<ArrayList<Integer>> alllist = FindPath(tree1,target);        for(ArrayList<Integer> list : alllist){    System.out.println(list.toString());    }}}