excel_sheet_column_number_171: solved

Author: austingebauer

excel_sheet_column_number_171/README.md

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+# 171. Excel Sheet Column Number
+
+https://leetcode.com/problems/excel-sheet-column-number/
+
+## Difficulty:
+
+Easy
+
+## Description
+
+Given a column title as appear in an Excel sheet, return its corresponding column number.
+
+For example:
+```
+A -> 1
+B -> 2
+C -> 3
+...
+Z -> 26
+AA -> 27
+AB -> 28 
+...
+```
+
+Example 1:
+```
+Input: "A"
+Output: 1
+```
+Example 2:
+```
+Input: "AB"
+Output: 28
+```
+Example 3:
+```
+Input: "ZY"
+Output: 701
+```
+
+Constraints:
+- 1 <= s.length <= 7
+- s consists only of uppercase English letters.
+- s is between "A" and "FXSHRXW".

excel_sheet_column_number_171/solution.go

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+package excel_sheet_column_number_171
+
+import "math"
+
+func titleToNumber(s string) int {
+	var res int
+	var exponent float64
+	for i := len(s) - 1; i > -1; i-- {
+		charNum := int(s[i]-'A') + 1
+		res += charNum * int(math.Pow(float64(26), exponent))
+		exponent++
+	}
+	return res
+}

excel_sheet_column_number_171/solution_test.go

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+package excel_sheet_column_number_171
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_titleToNumber(t *testing.T) {
+	type args struct {
+		s string
+	}
+	tests := []struct {
+		name string
+		args args
+		want int
+	}{
+		{
+			name: "excel sheet column number",
+			args: args{
+				s: "A",
+			},
+			want: 1,
+		},
+		{
+			name: "excel sheet column number",
+			args: args{
+				s: "AB",
+			},
+			want: 28,
+		},
+		{
+			name: "excel sheet column number",
+			args: args{
+				s: "ZY",
+			},
+			want: 701,
+		},
+		{
+			name: "excel sheet column number",
+			args: args{
+				s: "YB",
+			},
+			want: 652,
+		},
+		{
+			name: "excel sheet column number",
+			args: args{
+				s: "AAA",
+			},
+			want: 703,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equal(t, tt.want, titleToNumber(tt.args.s))
+		})
+	}
+}