LeetCode/112. PathSum

Link

• https://leetcode.com/problems/path-sum

Summary

When I was solving this problem, I was missing two things.

1. Not caring about negative numbers.
2. Not carefully reding a description.

The description says that adding up all the values along the path. However I was thinking that Adding up until we find a value. This kind of process of thinking should be prevented, the assumption and misunderstanding.

Solutions

public bool HasPathSum(TreeNode root, int sum)
{
    if (root == null) return false;
    if (sum - root.val == 0) return root.left == null && root.right == null ? true : HasPathSum(root.left, sum - root.val) || HasPathSum(root.right, sum - root.val);
    if (Math.Abs(sum - root.val) < 0) return false;
    return HasPathSum(root.left, sum - root.val) || HasPathSum(root.right, sum - root.val);
}