91 added

Author: aQua

Algorithms/0091.decode-ways/README.md

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+# [91. Decode Ways](https://leetcode.com/problems/decode-ways/)
+
+## 题目
+A message containing letters from `A-Z` is being encoded to numbers using the following mapping:
+
+```
+'A' -> 1
+'B' -> 2
+...
+'Z' -> 26
+```
+
+Given an encoded message containing digits, determine the total number of ways to decode it.
+
+```
+For example,
+Given encoded message "12",
+it could be decoded as "AB" (1 2) or "L" (12).
+The number of ways decoding "12" is 2.
+```
+
+## 解题思路
+
+见程序注释

Algorithms/0091.decode-ways/decode-ways.go

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+package Problem0091
+
+func numDecodings(s string) int {
+
+}

Algorithms/0091.decode-ways/decode-ways_test.go

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+package Problem0091
+
+import (
+	"testing"
+	"fmt"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type question struct {
+	para
+	ans
+}
+
+// para 是参数
+type para struct {
+	s string
+}
+
+// ans 是答案
+type ans struct {
+	one  int 
+}
+
+func Test_Problem0091(t *testing.T) {
+	ast := assert.New(t)
+
+	qs := []question{
+
+		question{
+			para{
+					,
+			},
+			ans{
+					,
+			},
+		},
+	
+		// 如需多个测试，可以复制上方元素。
+	}
+
+	for _, q := range qs {
+		a, p := q.ans, q.para
+		fmt.Printf("~~%v~~\n", p)
+
+		ast.Equal(a.one, numDecodings(p.  ), "输入:%v", p)
+	}
+}