Golang | Leetcode Golang题解之第236题二叉树的最近公共祖先

题目：

题解：

func lowestCommonAncestor(root, p, q *TreeNode) *TreeNode {
    parent := map[int]*TreeNode{}
    visited := map[int]bool{}
 
    var dfs func(*TreeNode)
    dfs = func(r *TreeNode) {
        if r == nil {
            return
        }
        if r.Left != nil {
            parent[r.Left.Val] = r
            dfs(r.Left)
        }
        if r.Right != nil {
            parent[r.Right.Val] = r
            dfs(r.Right)
        }
    }
    dfs(root)
 
    for p != nil {
        visited[p.Val] = true
        p = parent[p.Val]
    }
    for q != nil {
        if visited[q.Val] {
            return q
        }
        q = parent[q.Val]
    }
 
    return nil
}