_112.java

package com.fishercoder.solutions;

import com.fishercoder.common.classes.TreeNode;

/**112. 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.*/
public class _112 {
    public boolean hasPathSum(TreeNode root, int sum) {
        if(root == null) return false;
        if(root.val == sum && root.left == null && root.right == null) return true;
        return hasPathSum(root.left, sum - root.val) || hasPathSum(root.right, sum - root.val);
    }

}