LeetCode in TypeScript

112. Path Sum

Easy

Given the root of a binary tree and an integer targetSum, return true if the tree has a root-to-leaf path such that adding up all the values along the path equals targetSum.

A leaf is a node with no children.

Example 1:

Input: root = [5,4,8,11,null,13,4,7,2,null,null,null,1], targetSum = 22

Output: true

Example 2:

Input: root = [1,2,3], targetSum = 5

Output: false

Example 3:

Input: root = [1,2], targetSum = 0

Output: false

Constraints:

Solution

import { TreeNode } from '../../com_github_leetcode/treenode'

/**
 * Definition for a binary tree node.
 * class TreeNode {
 *     val: number
 *     left: TreeNode | null
 *     right: TreeNode | null
 *     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
 *         this.val = (val===undefined ? 0 : val)
 *         this.left = (left===undefined ? null : left)
 *         this.right = (right===undefined ? null : right)
 *     }
 * }
 */
function hasPathSum(root: TreeNode | null, targetSum: number): boolean {
    if (root === null) {
        return false
    }
    if (targetSum === root.val && root.left === null && root.right === null) {
        return true
    }
    return hasPathSum(root.left, targetSum - root.val) || hasPathSum(root.right, targetSum - root.val)
}

export { hasPathSum }