Created
December 12, 2020 09:40
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[golang] Given a BT, let's found the ancestor for the deepest leave/s
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/** | |
* Definition for a binary tree node. | |
* type TreeNode struct { | |
* Val int | |
* Left *TreeNode | |
* Right *TreeNode | |
* } | |
*/ | |
func lcaDeepestLeaves(root *TreeNode) *TreeNode { | |
levels := map[int][]*TreeNode{} | |
walk(root, &levels, 0) | |
// fmt.Println(levels) | |
ln := len(levels) | |
if ln == 1 { | |
return root | |
} | |
if len(levels[ln-1]) == 1 { | |
return levels[ln-1][0] | |
} | |
// search until we found a "father" | |
index := ln - 1 | |
for { | |
for _, leaf := range levels[index] { | |
if containsAll(leaf, levels[ln-1]) { | |
return leaf | |
} | |
} | |
// | |
index-- | |
if index == 0 { | |
break | |
} | |
} | |
return root | |
} | |
func containsAll(leaf *TreeNode, nodes []*TreeNode) bool { | |
array := []*TreeNode{} | |
toArray(leaf, &array) | |
hash := map[*TreeNode]bool{} | |
for _, a := range array { | |
for _, n := range nodes { | |
if a == n { | |
hash[a] = true | |
} | |
} | |
} | |
return len(hash) == len(nodes) | |
} | |
func toArray(leaf *TreeNode, array *[]*TreeNode) { | |
if leaf == nil { | |
return | |
} | |
toArray(leaf.Left, array) | |
*array = append(*array, leaf) | |
toArray(leaf.Right, array) | |
} | |
func walk(leaf *TreeNode, levels *map[int][]*TreeNode, level int) { | |
if leaf == nil { | |
return | |
} | |
walk(leaf.Left, levels, level + 1) | |
(*levels)[level] = append((*levels)[level], leaf) | |
walk(leaf.Right, levels, level + 1) | |
} |
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