NC9题解 | #二叉树中和为某一值的路径(二)#

类似于NC8

import java.util.*;

/*
 * public class TreeNode {
 *   int val = 0;
 *   TreeNode left = null;
 *   TreeNode right = null;
 * }
 */

public class Solution {
    /**
     * 
     * @param root TreeNode类 
     * @param sum int整型 
     * @return bool布尔型
     */
    ArrayList<ArrayList<Integer>> ll = new ArrayList<ArrayList<Integer>>();
    public boolean hasPathSum (TreeNode root, int sum) {
        // write code here
        ArrayList<Integer> path = new ArrayList();
        rec(root,path,sum);
        if(ll.size()>0){
            return true;
        }else{
            return false;
        }
    }
    public void rec(TreeNode root, ArrayList<Integer> path, int expectNumber){
        if(root == null){
            return;
        }
        ArrayList<Integer> newPath = new ArrayList(path);
        newPath.add(root.val);
        if(root.left != null){
            rec(root.left, newPath, expectNumber - root.val);
        }
        if(root.right != null){
            rec(root.right, newPath, expectNumber - root.val);
        }
        if(root.left == null && root.right == null){
            if(root.val == expectNumber){
                ll.add(newPath);
                System.out.println(Arrays.toString(ll.toArray()));
            }
        }
    }
}