package main

type TreeNode struct {
	Val   int
	Left  *TreeNode
	Right *TreeNode
}

func main() {

}
func pathSum(root *TreeNode, targetSum int) int {
	if root == nil {
		return 0
	}
	if root.Left == nil && root.Right == nil && root.Val == targetSum {
		return 1
	}
	hash := make(map[int]int)
	var culcalute func(root *TreeNode, hash map[int]int, total int, targetSum int) int
	culcalute = func(roottmp *TreeNode, hash map[int]int, total int, targetSum int) int {
		if roottmp == nil {
			return 0
		}
		restmp := 0
		hashtmp := make(map[int]int)
		for k, v := range hash {
			hashtmp[k] = v
		}
		totalnum := total + roottmp.Val
		if value, ok := hash[totalnum-targetSum]; ok {
			restmp = restmp + value
		}
		hashtmp[totalnum]++
		res := culcalute(roottmp.Left, hashtmp, totalnum, targetSum) + culcalute(roottmp.Right, hashtmp, totalnum, targetSum) + restmp
		return res
	}
	hash[0]++
	result := culcalute(root, hash, 0, targetSum)
	return result
}