Golang | Leetcode Golang题解之第437题路径总和III
题目：
题解：
func pathSum(root *TreeNode, targetSum int) (ans int) {
preSum := map[int64]int{0: 1}
var dfs func(*TreeNode, int64)
dfs = func(node *TreeNode, curr int64) {
if node == nil {
return
}
curr += int64(node.Val)
ans += preSum[curr-int64(targetSum)]
preSum[curr]++
dfs(node.Left, curr)
dfs(node.Right, curr)
preSum[curr]--
return
}
dfs(root, 0)
return
}