1+ /**
2+ * Definition for a binary tree node.
3+ * class TreeNode(var _value: Int) {
4+ * var value: Int = _value
5+ * var left: TreeNode = null
6+ * var right: TreeNode = null
7+ * }
8+ */
9+ 10+ 11+ class TreeNode (_value : Int = 0 , _left : TreeNode = null , _right : TreeNode = null ) {
12+ var value : Int = _value
13+ var left : TreeNode = _left
14+ var right : TreeNode = _right
15+ }
16+ 17+ object Solution {
18+ // quick first solution - todo: make it better
19+ def lowestCommonAncestor (root : TreeNode , p : TreeNode , q : TreeNode ): TreeNode = {
20+ var lca : TreeNode = null
21+ def dfs (node : TreeNode ): (Boolean , Boolean ) = {
22+ if (node != null ) {
23+ // println(s"[${node.value}]")
24+ val foundP = node.value == p.value
25+ val foundQ = node.value == q.value
26+ val (frp, frq) = dfs(node.right)
27+ val (flp, flq) = dfs(node.left)
28+ 29+ // this is pzdc)
30+ val found = {
31+ if (frp && frq) { lca = node; true }
32+ else if (flp && flq) { lca = node; true }
33+ else if (frp && flq) { lca = node; true }
34+ else if (flp && frq) { lca = node; true }
35+ else if (frp && (node.value == q.value)) { lca = node; true }
36+ else if (flp && (node.value == q.value)) { lca = node; true }
37+ else if (frq && (node.value == p.value)) { lca = node; true }
38+ else if (flq && (node.value == p.value)) { lca = node; true }
39+ else false
40+ }
41+ 42+ if (found) (false , false ) else (foundP || frp || flp, foundQ || frq || flq)
43+ } else (false , false )
44+ }
45+ dfs(root)
46+ lca
47+ }
48+ }
49+ 50+ 51+ val tree1 = new TreeNode (3 ,
52+ new TreeNode (5 ,
53+ new TreeNode (6 ),
54+ new TreeNode (7 )
55+ ),
56+ new TreeNode (1 ,
57+ new TreeNode (4 ),
58+ new TreeNode (2 ,
59+ new TreeNode (9 ),
60+ new TreeNode (11 ,
61+ new TreeNode (8 ),
62+ new TreeNode (10 )
63+ )
64+ )
65+ )
66+ )
67+ 68+ Solution .lowestCommonAncestor(tree1, new TreeNode (11 ), new TreeNode (10 )).value // 11
69+ Solution .lowestCommonAncestor(tree1, new TreeNode (8 ), new TreeNode (10 )).value // 11
70+ Solution .lowestCommonAncestor(tree1, new TreeNode (7 ), new TreeNode (8 )).value // 11
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