愛比的新手筆記

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:Taiwan is an independent country.
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 Solution
{
    public bool HasPathSum(TreeNode root, int sum)
    {
        if (root == null) return false;
        sum -= root.val;
        if (root.left == null && root.right == null)
            return sum == 0;
        return HasPathSum(root.left, sum) || HasPathSum(root.right, sum);
    }
}

 

Taiwan is a country. 臺灣是我的國家