From 84b5a0d759fdd8f8f151397c8650ba121d5780e1 Mon Sep 17 00:00:00 2001
From: Vasko Zdravevski <vaskoz@users.noreply.github.com>
Date: Tue, 1 Jan 2019 23:09:38 -0700
Subject: [PATCH 1/2] day 117: return minLevel and minSum of a binary tree

---
 day117/problem.go      | 41 ++++++++++++++++++++++++++
 day117/problem_test.go | 65 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 106 insertions(+)
 create mode 100644 day117/problem.go
 create mode 100644 day117/problem_test.go

diff --git a/day117/problem.go b/day117/problem.go
new file mode 100644
index 0000000..f284fd3
--- /dev/null
+++ b/day117/problem.go
@@ -0,0 +1,41 @@
+package day117
+
+// BinaryTree is a binary tree of integers.
+type BinaryTree struct {
+	Value       int
+	Left, Right *BinaryTree
+}
+
+// MinimumSumLevel returns both the 1-based level and sum of that level.
+// Runs in O(N) time and O(1) extra space.
+// If you pass in "nil", the sum is 0 and the level is 0.
+func MinimumSumLevel(tree *BinaryTree) (minSum int, minLevel int) {
+	if tree == nil {
+		return
+	}
+	minSum = int(^uint(0) >> 1)
+	minLevel = minSum
+	current := make([]*BinaryTree, 0, 1)
+	current = append(current, tree)
+	level := 1
+	for len(current) != 0 {
+		nextLevel := make([]*BinaryTree, 0, 2*cap(current))
+		var sum int
+		for _, ptr := range current {
+			sum += ptr.Value
+			if ptr.Left != nil {
+				nextLevel = append(nextLevel, ptr.Left)
+			}
+			if ptr.Right != nil {
+				nextLevel = append(nextLevel, ptr.Right)
+			}
+		}
+		if sum < minSum {
+			minSum = sum
+			minLevel = level
+		}
+		level++
+		current = nextLevel
+	}
+	return
+}
diff --git a/day117/problem_test.go b/day117/problem_test.go
new file mode 100644
index 0000000..f5aeff1
--- /dev/null
+++ b/day117/problem_test.go
@@ -0,0 +1,65 @@
+package day117
+
+import "testing"
+
+var testcases = []struct {
+	tree             *BinaryTree
+	minLevel, minSum int
+}{
+	{nil, 0, 0},
+	{&BinaryTree{5,
+		&BinaryTree{10, nil, nil},
+		&BinaryTree{20, nil, nil}},
+		1,
+		5},
+	{&BinaryTree{5,
+		&BinaryTree{10, nil, nil},
+		&BinaryTree{-20, nil, nil}},
+		2,
+		-10},
+	{&BinaryTree{5,
+		&BinaryTree{10,
+			&BinaryTree{30,
+				nil,
+				&BinaryTree{0,
+					&BinaryTree{-7, nil, nil},
+					&BinaryTree{-9, nil, nil}}},
+			nil},
+		&BinaryTree{20,
+			nil,
+			&BinaryTree{0,
+				&BinaryTree{3, nil, nil},
+				&BinaryTree{5, nil, nil}}}},
+		5,
+		-16},
+	{&BinaryTree{5,
+		&BinaryTree{10,
+			&BinaryTree{30,
+				nil,
+				&BinaryTree{-9, nil, nil}},
+			nil},
+		&BinaryTree{20,
+			nil,
+			&BinaryTree{0,
+				&BinaryTree{3, nil, nil},
+				&BinaryTree{5, nil, nil}}}},
+		4,
+		-1},
+}
+
+func TestMinimumSumLevel(t *testing.T) {
+	t.Parallel()
+	for _, tc := range testcases {
+		if sum, level := MinimumSumLevel(tc.tree); sum != tc.minSum && level != tc.minLevel {
+			t.Errorf("Expected (%d,%d), but got (%d,%d)", tc.minSum, tc.minLevel, sum, level)
+		}
+	}
+}
+
+func BenchmarkMinimumSumLevel(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for _, tc := range testcases {
+			MinimumSumLevel(tc.tree)
+		}
+	}
+}

From 946f43d197c14c563736360e145a31c0f00fedb3 Mon Sep 17 00:00:00 2001
From: Vasko Zdravevski <vaskoz@users.noreply.github.com>
Date: Tue, 1 Jan 2019 23:10:30 -0700
Subject: [PATCH 2/2] add day 117 to readme

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

diff --git a/README.md b/README.md
index 83436b0..6ddb8cd 100644
--- a/README.md
+++ b/README.md
@@ -126,6 +126,7 @@ problems from
 * [Day 114](https://github.com/vaskoz/dailycodingproblem-go/issues/237)
 * [Day 115](https://github.com/vaskoz/dailycodingproblem-go/issues/238)
 * [Day 116](https://github.com/vaskoz/dailycodingproblem-go/issues/242)
+* [Day 117](https://github.com/vaskoz/dailycodingproblem-go/issues/245)
 * [Day 118](https://github.com/vaskoz/dailycodingproblem-go/issues/246)
 * [Day 120](https://github.com/vaskoz/dailycodingproblem-go/issues/248)
 * [Day 122](https://github.com/vaskoz/dailycodingproblem-go/issues/252)