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 1return true, as there exist a root-to-leaf path 5->4->11->2 which sum is 22.
recursion解
public boolean hasPathSum(TreeNode root, int sum) {
if (root == null) return false;
if (root.left == null && root.right == null) {
if (sum == root.val) {
return true;
}
}
return hasPathSum(root.left, sum - root.val) || hasPathSum(root.right, sum - root.val);
}