题解 | #二叉树中和为某一值的路径(一)#
二叉树中和为某一值的路径(一)
https://www.nowcoder.com/practice/508378c0823c423baa723ce448cbfd0c
/*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)
* }
* }
*/
/**
* 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
*
* @param root TreeNode类
* @param sum int整型
* @return bool布尔型
*/
export function hasPathSum(root: TreeNode, sum: number): boolean {
// write code here
if (root === null ) return false
if (root.val === sum) {
if (!root.left && !root.right) return true
return (root.left && hasSum(root.left, 0)) || (root.right && hasSum(root.right, 0))
}
return hasSum(root, sum)
}
const hasSum = (node: TreeNode, sum: number): boolean => {
if (node === null) return sum === 0
const rest = sum - node.val
return hasSum(node.left, rest) || hasSum(node.right, rest)
}