leetcode 113 Path Sum II ----- java

Posted 2020-08-16 xiaoba1203

Given a binary tree and a sum, find all root-to-leaf paths where each path‘s sum equals the given sum.

For example:
Given the below binary tree and sum = 22,

              5
             /             4   8
           /   /           11  13  4
         /  \    /         7    2  5   1

return

[
   [5,4,11,2],
   [5,8,4,5]
]

上一道题的延伸，求出所有结果。

 

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    List list = new ArrayList<List<Integer>>();
    public List<List<Integer>> pathSum(TreeNode root, int sum) {
        
        if( root == null)
            return list;
        getResult(root,sum,new ArrayList<Integer>(),0);
        return list;
    }

    public void getResult(TreeNode root,int sum,List<Integer> ans,int pos){

        if( root == null )
            return ;
        ans.add(root.val);
        if( sum == root.val ){
            if( root.left == null && root.right == null){
                ArrayList result = new ArrayList<Integer>();
                result.addAll(ans);
                list.add(result);
            }
        }
        getResult(root.left,sum-root.val,ans,pos+1);
        getResult(root.right,sum-root.val,ans,pos+1);
        ans.remove(pos);
        return ;

    }
}