二叉树中和为某一值的路径

二叉树中和为某一值的路径

题目描述

代码

[code]/*
public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

    public TreeNode(int val) {
        this.val = val;

    }

}
*/
import java.util.ArrayList;
public class Solution {

    ArrayList list=new ArrayList();
    ArrayList stack=new ArrayList();
    public ArrayList<ArrayList<Integer>> FindPath(TreeNode root,int target) {

       if(root==null) return list;
       return FindPath( root, target,0); 

    }
    public ArrayList<ArrayList<Integer>> FindPath(TreeNode root,
                          int target,

                          int sum) 
    {

         //前序遍历
         if(root!=null){
             //ele=new  ArrayList<Integer>();
             int val=root.val;
             sum+=val;
             boolean isleaf=(root.left==null&&root.right==null);
             stack.add(val);

             if(sum==target&&isleaf){

                 ArrayList path=new ArrayList();
                 for(int i=0;i<stack.size();i++){
                      path.add(stack.get(i));
                 }
                 list.add(path);

             }

             FindPath( root.left, target,sum);
             FindPath( root.right, target,sum);

             if(stack.size()>0){
                 stack.remove(stack.size()-1);
             }
             return list;
         }
         return null;
    }
}