From de52857387cd8f72494f972439211dba77bf0593 Mon Sep 17 00:00:00 2001
From: Openset <openset@users.noreply.github.com>
Date: Fri, 11 Jan 2019 10:50:05 +0800
Subject: [PATCH 1/2] Add: Monotonic Array

---
 problems/monotonic-array/monotonic_array.go   | 12 ++++++
 .../monotonic-array/monotonic_array_test.go   | 42 +++++++++++++++++++
 2 files changed, 54 insertions(+)

diff --git a/problems/monotonic-array/monotonic_array.go b/problems/monotonic-array/monotonic_array.go
index bc9bae6e1..1c5204e03 100644
--- a/problems/monotonic-array/monotonic_array.go
+++ b/problems/monotonic-array/monotonic_array.go
@@ -1 +1,13 @@
 package monotonic_array
+
+func isMonotonic(A []int) bool {
+	t, f := 0, 0
+	for i, v := range A[1:] {
+		if v > A[i] {
+			t++
+		} else if v < A[i] {
+			f++
+		}
+	}
+	return t == 0 || f == 0
+}
diff --git a/problems/monotonic-array/monotonic_array_test.go b/problems/monotonic-array/monotonic_array_test.go
index bc9bae6e1..16a609a8a 100644
--- a/problems/monotonic-array/monotonic_array_test.go
+++ b/problems/monotonic-array/monotonic_array_test.go
@@ -1 +1,43 @@
 package monotonic_array
+
+import "testing"
+
+type caseType struct {
+	input    []int
+	expected bool
+}
+
+func TestIsMonotonic(t *testing.T) {
+	tests := [...]caseType{
+		{
+			input:    []int{1, 2, 2, 3},
+			expected: true,
+		},
+		{
+			input:    []int{6, 5, 4, 4},
+			expected: true,
+		},
+		{
+			input:    []int{1, 3, 2},
+			expected: false,
+		},
+		{
+			input:    []int{1, 2, 4, 5},
+			expected: true,
+		},
+		{
+			input:    []int{1, 1, 1},
+			expected: true,
+		},
+		{
+			input:    []int{1, 2, 3, 3, 3, 2, 1},
+			expected: false,
+		},
+	}
+	for _, tc := range tests {
+		output := isMonotonic(tc.input)
+		if output != tc.expected {
+			t.Fatalf("input: %v, output: %v, expected: %v", tc.input, output, tc.expected)
+		}
+	}
+}

From 5a203568f85a831f9509ac0638e7678a685cab97 Mon Sep 17 00:00:00 2001
From: Openset <openset@users.noreply.github.com>
Date: Fri, 11 Jan 2019 11:00:28 +0800
Subject: [PATCH 2/2] Update: Monotonic Array

---
 problems/monotonic-array/monotonic_array.go | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/problems/monotonic-array/monotonic_array.go b/problems/monotonic-array/monotonic_array.go
index 1c5204e03..457484c26 100644
--- a/problems/monotonic-array/monotonic_array.go
+++ b/problems/monotonic-array/monotonic_array.go
@@ -1,13 +1,13 @@
 package monotonic_array
 
 func isMonotonic(A []int) bool {
-	t, f := 0, 0
+	increasing, decreasing := true, true
 	for i, v := range A[1:] {
 		if v > A[i] {
-			t++
+			decreasing = false
 		} else if v < A[i] {
-			f++
+			increasing = false
 		}
 	}
-	return t == 0 || f == 0
+	return increasing || decreasing
 }