leetcode-java-257. Binary Tree Paths

/*思路：1.采用递归左子树递归找到路径（根节点+左子树）右子树递归找到路径（根节点+右子树）2.递归停止条件：递归到叶子节点时终止，即root.left==null && root.right == null时,将字符串add到result中。 */ public class Solution {     public List<String> binaryTreePaths(TreeNode root) {         List<String> result = new LinkedList<String>();         if(root == null) {             return result;         }         findPaths(result,"",root);         return result;     }     public void findPaths(List<String> result,String temp,TreeNode root) {         if(root == null) {             return;         }         if(root.left == null && root.right == null) {             result.add(temp+Integer.toString(root.val));             return;         }         findPaths(result,temp+Integer.toString(root.val)+"->",root.left);         findPaths(result,temp+Integer.toString(root.val)+"->",root.right);     } }