From 2bb078c03a91b612d0e57162de93a0fdcbade117 Mon Sep 17 00:00:00 2001
From: Vasko Zdravevski <vaskoz@users.noreply.github.com>
Date: Tue, 18 Feb 2020 19:44:58 -0700
Subject: [PATCH 1/2] day 453: cleaned up day 125

---
 day453/problem.go      | 46 ++++++++++++++++++++++++++++++++++++++++++
 day453/problem_test.go | 44 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 90 insertions(+)
 create mode 100644 day453/problem.go
 create mode 100644 day453/problem_test.go

diff --git a/day453/problem.go b/day453/problem.go
new file mode 100644
index 0000000..6a4bd1a
--- /dev/null
+++ b/day453/problem.go
@@ -0,0 +1,46 @@
+package day453
+
+// BST is an integer binary search tree.
+type BST struct {
+	Val         int
+	Left, Right *BST
+}
+
+// FindTwoSumKInBST returns a slice of integer nodes that sum to K.
+// If no two nodes exist that sum to K, then return nil.
+// Runs in O(N log N) where N is the size of the BST.
+func FindTwoSumKInBST(head *BST, k int) []int {
+	return inorder(head, head, k, []int{})
+}
+
+func inorder(head, current *BST, k int, result []int) []int {
+	if current == nil {
+		return result
+	}
+
+	if leftResult := inorder(head, current.Left, k, result); len(leftResult) == 2 {
+		return leftResult
+	}
+
+	if node := searchBST(head, k-current.Val); node != nil && node != current {
+		return []int{current.Val, node.Val}
+	}
+
+	if rightResult := inorder(head, current.Right, k, result); len(rightResult) == 2 {
+		return rightResult
+	}
+
+	return result
+}
+
+func searchBST(head *BST, target int) *BST {
+	if head == nil {
+		return nil
+	}
+
+	if target == head.Val {
+		return head
+	}
+
+	return searchBST(head.Right, target)
+}
diff --git a/day453/problem_test.go b/day453/problem_test.go
new file mode 100644
index 0000000..a2e3d62
--- /dev/null
+++ b/day453/problem_test.go
@@ -0,0 +1,44 @@
+package day453
+
+import (
+	"reflect"
+	"testing"
+)
+
+// nolint
+var testcases = []struct {
+	head     *BST
+	k        int
+	expected []int
+}{
+	{&BST{10, &BST{5, nil, nil}, &BST{
+		15, &BST{11, nil, nil}, &BST{15, nil, nil},
+	}}, 20, []int{5, 15}},
+	{&BST{10, &BST{5, nil, nil}, &BST{
+		15, &BST{11, nil, nil}, &BST{15, nil, nil},
+	}}, 100, []int{}},
+	{&BST{10, &BST{5, nil, nil}, &BST{
+		15, &BST{11, nil, nil}, &BST{15, nil, nil},
+	}}, 15, []int{5, 10}},
+	{&BST{10, &BST{5, nil, nil}, &BST{
+		15, &BST{11, nil, nil}, &BST{15, nil, nil},
+	}}, 26, []int{11, 15}},
+}
+
+func TestFindTwoSumKInBST(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range testcases {
+		if result := FindTwoSumKInBST(tc.head, tc.k); !reflect.DeepEqual(result, tc.expected) {
+			t.Errorf("Expected %v got %v", tc.expected, result)
+		}
+	}
+}
+
+func BenchmarkFindTwoSumInBST(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for _, tc := range testcases {
+			FindTwoSumKInBST(tc.head, tc.k)
+		}
+	}
+}

From 1356454bcd92fc149aafa31d19e9d317656347b8 Mon Sep 17 00:00:00 2001
From: Vasko Zdravevski <vaskoz@users.noreply.github.com>
Date: Tue, 18 Feb 2020 19:45:19 -0700
Subject: [PATCH 2/2] add day 453 to readme

---
 README.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/README.md b/README.md
index af36924..4b03bdf 100644
--- a/README.md
+++ b/README.md
@@ -450,4 +450,5 @@ problems from
 * [Day 450](https://github.com/vaskoz/dailycodingproblem-go/issues/909)
 * [Day 451](https://github.com/vaskoz/dailycodingproblem-go/issues/911)
 * [Day 452](https://github.com/vaskoz/dailycodingproblem-go/issues/913)
+* [Day 453](https://github.com/vaskoz/dailycodingproblem-go/issues/915)