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Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum. For example: Given the below binary tree and sum = 22, 5 / 4 8 / / 11 13 4 / \ 7 2 1 return true, as there exist a root-to-leaf path 5->4->11->2 which sum is 22.
/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ public class Solution { public boolean hasPathSum(TreeNode root, int sum) { if(root == null) return false; ArrayList<TreeNode> nodes = new ArrayList<TreeNode>(); ArrayList<Integer> values = new ArrayList<Integer>(); nodes.add(root); values.add(root.val); while(!nodes.isEmpty()){ TreeNode curr = nodes.get(0); int sumValue = values.get(0); if(curr.left == null && curr.right == null && sumValue==sum){ return true; } if(curr.left != null){ nodes.add(curr.left); values.add(sumValue+curr.left.val); } if(curr.right != null){ nodes.add(curr.right); values.add(sumValue+curr.right.val); } nodes.remove(0); values.remove(0); } return false; } }
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原文地址:http://www.cnblogs.com/incrediblechangshuo/p/5476414.html