0112-path-sum.java

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 * int val;
 * TreeNode left;
 * TreeNode right;
 * TreeNode() {}
 * TreeNode(int val) { this.val = val; }
 * TreeNode(int val, TreeNode left, TreeNode right) {
 * this.val = val;
 * this.left = left;
 * this.right = right;
 * }
 * }
 */
classSolution {
privatebooleanisLeafNode(TreeNodenode) {
return ((node.left == null) && (node.right == null));
 }

publicbooleanhasPathSum(TreeNoderoot, inttargetSum) {
// Edge case: No nodes
if(root == null) {
returnfalse;
 }

targetSum -= root.val;
if(isLeafNode(root)) {
return (targetSum == 0);
 }
returnhasPathSum(root.left, targetSum) || hasPathSum(root.right, targetSum);
 }
}