From 74d01e508a643f5fe01575d8bc3dc775316d87eb Mon Sep 17 00:00:00 2001
From: YDZ <ydz627@gmail.com>
Date: Thu, 8 Aug 2019 21:27:24 +0800
Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=20problem=20541?=
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---
 .../541. Reverse String II.go                 | 17 ++++++
 .../541. Reverse String II_test.go            | 58 +++++++++++++++++++
 Algorithms/0541. Reverse String II/README.md  | 31 ++++++++++
 3 files changed, 106 insertions(+)
 create mode 100644 Algorithms/0541. Reverse String II/541. Reverse String II.go
 create mode 100644 Algorithms/0541. Reverse String II/541. Reverse String II_test.go
 create mode 100755 Algorithms/0541. Reverse String II/README.md

diff --git a/Algorithms/0541. Reverse String II/541. Reverse String II.go b/Algorithms/0541. Reverse String II/541. Reverse String II.go
new file mode 100644
index 00000000..fe300150
--- /dev/null
+++ b/Algorithms/0541. Reverse String II/541. Reverse String II.go	
@@ -0,0 +1,17 @@
+package leetcode
+
+func reverseStr(s string, k int) string {
+	if k > len(s) {
+		k = len(s)
+	}
+	for i := 0; i < len(s); i = i + 2*k {
+		if len(s)-i >= k {
+			ss := revers(s[i : i+k])
+			s = s[:i] + ss + s[i+k:]
+		} else {
+			ss := revers(s[i:])
+			s = s[:i] + ss
+		}
+	}
+	return s
+}
diff --git a/Algorithms/0541. Reverse String II/541. Reverse String II_test.go b/Algorithms/0541. Reverse String II/541. Reverse String II_test.go
new file mode 100644
index 00000000..358f0aa1
--- /dev/null
+++ b/Algorithms/0541. Reverse String II/541. Reverse String II_test.go	
@@ -0,0 +1,58 @@
+package leetcode
+
+import (
+	"fmt"
+	"testing"
+)
+
+type question541 struct {
+	para541
+	ans541
+}
+
+// para 是参数
+// one 代表第一个参数
+type para541 struct {
+	s string
+	k int
+}
+
+// ans 是答案
+// one 代表第一个答案
+type ans541 struct {
+	one string
+}
+
+func Test_Problem541(t *testing.T) {
+
+	qs := []question541{
+
+		question541{
+			para541{"abcdefg", 2},
+			ans541{"bacdfeg"},
+		},
+
+		question541{
+			para541{"abcdefg", 5},
+			ans541{"edcbafg"},
+		},
+
+		question541{
+			para541{"abcd", 4},
+			ans541{"dcba"},
+		},
+
+		question541{
+			para541{"", 100},
+			ans541{""},
+		},
+	}
+
+	fmt.Printf("------------------------Leetcode Problem 541------------------------\n")
+
+	for _, q := range qs {
+		_, p := q.ans541, q.para541
+		fmt.Printf("【input】:%v       【output】:%v\n", p, reverseStr(p.s, p.k))
+	}
+	fmt.Printf("\n\n\n")
+}
diff --git a/Algorithms/0541. Reverse String II/README.md b/Algorithms/0541. Reverse String II/README.md
new file mode 100755
index 00000000..f368ba5f
--- /dev/null
+++ b/Algorithms/0541. Reverse String II/README.md	
@@ -0,0 +1,31 @@
+# [541. Reverse String II](https://leetcode.com/problems/reverse-string-ii/)
+
+
+## 题目:
+
+Given a string and an integer k, you need to reverse the first k characters for every 2k characters counting from the start of the string. If there are less than k characters left, reverse all of them. If there are less than 2k but greater than or equal to k characters, then reverse the first k characters and left the other as original.
+
+**Example:**
+
+    Input: s = "abcdefg", k = 2
+    Output: "bacdfeg"
+
+**Restrictions:**
+
+1. The string consists of lower English letters only.
+2. Length of the given string and k will in the range [1, 10000]
+
+## 题目大意
+
+给定一个字符串和一个整数 k，你需要对从字符串开头算起的每个 2k 个字符的前k个字符进行反转。如果剩余少于 k 个字符，则将剩余的所有全部反转。如果有小于 2k 但大于或等于 k 个字符，则反转前 k 个字符，并将剩余的字符保持原样。
+
+要求:
+
+- 该字符串只包含小写的英文字母。
+- 给定字符串的长度和 k 在[1, 10000]范围内。
+
+
+## 解题思路
+
+- 要求按照一定规则反转字符串：每 `2 * K` 长度的字符串，反转前 `K` 个字符，后 `K` 个字符串保持不变；对于末尾不够 `2 * K` 的字符串，如果长度大于 `K`，那么反转前 `K` 个字符串，剩下的保持不变。如果长度小于 `K`，则把小于 `K` 的这部分字符串全部反转。
+- 这一题是简单题，按照题意反转字符串即可。