From d35c46bacf9b8ad80b4eddda466e772f1b8527bf Mon Sep 17 00:00:00 2001
From: openset <openset@users.noreply.github.com>
Date: Tue, 26 Feb 2019 12:01:51 +0800
Subject: [PATCH] Add: Excel Sheet Column Title

---
 .../excel_sheet_column_title.go               |  7 +++
 .../excel_sheet_column_title_test.go          | 54 +++++++++++++++++++
 2 files changed, 61 insertions(+)

diff --git a/problems/excel-sheet-column-title/excel_sheet_column_title.go b/problems/excel-sheet-column-title/excel_sheet_column_title.go
index 05ad7ad45..954d1d263 100644
--- a/problems/excel-sheet-column-title/excel_sheet_column_title.go
+++ b/problems/excel-sheet-column-title/excel_sheet_column_title.go
@@ -1 +1,8 @@
 package excel_sheet_column_title
+
+func convertToTitle(n int) string {
+	if n < 27 {
+		return string(n - 1 + 'A')
+	}
+	return convertToTitle((n-1)/26) + string((n-1)%26+'A')
+}
diff --git a/problems/excel-sheet-column-title/excel_sheet_column_title_test.go b/problems/excel-sheet-column-title/excel_sheet_column_title_test.go
index 05ad7ad45..9ce8afc35 100644
--- a/problems/excel-sheet-column-title/excel_sheet_column_title_test.go
+++ b/problems/excel-sheet-column-title/excel_sheet_column_title_test.go
@@ -1 +1,55 @@
 package excel_sheet_column_title
+
+import "testing"
+
+type caseType struct {
+	input    int
+	expected string
+}
+
+func TestConvertToTitle(t *testing.T) {
+	tests := [...]caseType{
+		{
+			input:    1,
+			expected: "A",
+		},
+		{
+			input:    3,
+			expected: "C",
+		},
+		{
+			input:    26,
+			expected: "Z",
+		},
+		{
+			input:    52,
+			expected: "AZ",
+		},
+		{
+			input:    27,
+			expected: "AA",
+		},
+		{
+			input:    28,
+			expected: "AB",
+		},
+		{
+			input:    701,
+			expected: "ZY",
+		},
+		{
+			input:    703,
+			expected: "AAA",
+		},
+		{
+			input:    16900,
+			expected: "XYZ",
+		},
+	}
+	for _, tc := range tests {
+		output := convertToTitle(tc.input)
+		if output != tc.expected {
+			t.Fatalf("input: %v, output: %v, expected: %v", tc.input, output, tc.expected)
+		}
+	}
+}