Path Sum

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;
		}
		LinkedList<TreeNode> linkedList = new LinkedList<TreeNode>();
		LinkedList<Integer> linkedList2 = new LinkedList<Integer>();
		linkedList.add(root);
		linkedList2.add(root.val);

		while (!linkedList.isEmpty()) {
			TreeNode poll = linkedList.poll();
			Integer poll2 = linkedList2.poll();
			if (poll.left == null && poll.right == null && sum == poll2) {
				return true;
			}
			if (poll.left != null) {
				linkedList.add(poll.left);
				linkedList2.add(poll.left.val+poll2);
			}
			if (poll.right != null) {
				linkedList.add(poll.right);
				linkedList2.add(poll.right.val+poll2);
			}
		}
		return false;
	}
}