题解 | #二叉树中和为某一值的路径(三)#
二叉树中和为某一值的路径(三)
https://www.nowcoder.com/practice/965fef32cae14a17a8e86c76ffe3131f
/*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 int整型
*/
export function FindPath(root: TreeNode, sum: number): number {
// write code here
if (root === null) return 0
let count = 0
// compute current node
const pathCount = (root: TreeNode, sum: number): number => {
if (root === null) return 0
const rest = sum - root.val
if (rest === 0) {
count++
}
const leftCount = pathCount(root.left, rest)
const rightCount = pathCount(root.right, rest)
return count + leftCount + rightCount
}
// compute every node
const allPath = (root: TreeNode, sum: number): number => {
if (root === null) return
pathCount(root, sum)
allPath(root.left, sum)
allPath(root.right, sum)
}
allPath(root, sum)
return count
}
