[Leetcode] path sum

 1 /** 2  * Definition for binary tree 3  * public class TreeNode { 4  *     int val; 5  *     TreeNode left; 6  *     TreeNode right; 7  *     TreeNode(int x) { val = x; } 8  * } 9  */10 public class Solution {11     public boolean hasPathSum(TreeNode root, int sum) {12         int tmpSum=0;13         Stack<TreeNode> nodeStack = new Stack<TreeNode>();14         TreeNode nowNode = root;15         boolean popNode = false;16         17         if (root==null) return false;18         if (root.val==sum && root.left==null && root.right==null) return true;19         20         while (!(nowNode==root && popNode)) {21             if (!popNode) {22                 if (nowNode == null) {23                     popNode = true;24                 } else {25                     tmpSum += nowNode.val;26                     nodeStack.push(nowNode);27                     nowNode = nowNode.left;28                 }29             } else {30                 if (nowNode == nodeStack.peek().right) {31                     if (nowNode==null && tmpSum==sum && nodeStack.peek().left==null) return true;32                     nowNode = nodeStack.pop();33                     tmpSum -= nowNode.val;34                 } else {35                     nowNode = nodeStack.peek().right;36                     popNode = false;37                 }38             }39         }40         return false;41     }42 }

 

[Leetcode] path sum