Fun with trees: max sum

Instructions:

Fun with trees: max sum

Solution:

//https://www.codewars.com/kata/57e5279b7cf1aea5cf000359/train/java
import java.util.ArrayList;
class Solution{
    static int maxSum(TreeNode root){
        ArrayList<ArrayList<Integer>> allPaths = new FindShortestBTPath().findAllPath(root);
        int max = 0;
        for(ArrayList<Integer> path: paths){
            int sum = 0;
            for(Integer x : path){
                sum += x;
            }    
            if(sum > max){
                max = sum;
            }    
        }    
        return max;
    }    
    private static class FindShortestBTPath{
        private ArrayList<ArrayList<Integer>> allPaths = new ArrayList<ArrayList<Integer>>();
        private ArrayList<Integer> onePath = ArrayList<Integer>();
        public ArrayList<ArrayList<Integer>> findAllPath(TreeNode root){
            if(root == null){
                return allPaths;
            }    
            onePath.add(root.value);
            if(root.left == null && root.right == null){
                allPaths.add(newArrayList<Integer>(onePath));                
            }    
            findAllPath(root.left);
            findAllPath(root.right);
            onePath.remove(onePath.size() - 1);
            return allPaths;
        }    
    }    
}

Example Test:

https://www.codewars.com/kata/57e5279b7cf1aea5cf000359/train/java

Reference

二叉樹中全部的路徑（從根節點到葉子結點）