115 added

Author: aQua

Algorithms/0115.distinct-subsequences/README.md

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+# [115. Distinct Subsequences](https://leetcode.com/problems/distinct-subsequences/)
+
+## 题目
+Given a string S and a string T, count the number of distinct subsequences of S which equals T.
+
+A subsequence of a string is a new string which is formed from the original string by deleting some (can be none) of the characters without disturbing the relative positions of the remaining characters. (ie, "ACE" is a subsequence of "ABCDE" while "AEC" is not).
+
+Here is an example:
+```
+S = "rabbbit", T = "rabbit"
+Return 3.
+```
+
+## 解题思路
+
+见程序注释

Algorithms/0115.distinct-subsequences/distinct-subsequences.go

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+package Problem0115
+
+func numDistinct(s string, t string) int {
+	return 3
+}

Algorithms/0115.distinct-subsequences/distinct-subsequences_test.go

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+package Problem0115
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_Problem0115(t *testing.T) {
+	ast := assert.New(t)
+
+	// tcs is testcase slice
+	tcs := []struct {
+		s   string
+		t   string
+		ans int
+	}{
+
+		{
+			"rabbbit",
+			"rabbit",
+			3,
+		},
+
+		// 可以多个 testcase
+	}
+
+	for _, tc := range tcs {
+		fmt.Printf("~~%v~~\n", tc)
+
+		ast.Equal(tc.ans, numDistinct(tc.s, tc.t), "输入:%v", tc)
+	}
+}