From 95ca64dc6c886342e8a2105d3018b2712f0e3abc Mon Sep 17 00:00:00 2001
From: yi-ge <a@wyr.me>
Date: Thu, 28 May 2020 06:31:10 +0800
Subject: [PATCH] =?UTF-8?q?add:=20=E5=AD=97=E7=AC=A6=E4=B8=B2=E8=A7=A3?=
 =?UTF-8?q?=E7=A0=81?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 README.md                        |  5 +++++
 src/stack/decode-string.js       | 36 ++++++++++++++++++++++++++++++++
 test/stack/decode-string.test.js |  7 +++++++
 3 files changed, 48 insertions(+)
 create mode 100644 src/stack/decode-string.js
 create mode 100644 test/stack/decode-string.test.js

diff --git a/README.md b/README.md
index 96258db..3fc55ab 100644
--- a/README.md
+++ b/README.md
@@ -369,6 +369,11 @@ LeetCode 与 LintCode 解题记录。此为个人练习仓库，代码中对重
   - LeetCode 155. 最小栈 <https://leetcode-cn.com/problems/min-stack/>
   - LintCode 12. 带最小值操作的栈 <https://www.lintcode.com/problem/min-stack/description>
 
+- [字符串解码](src/stack/decode-string.js)
+
+  - LeetCode 394. 字符串解码 <https://leetcode-cn.com/problems/decode-string/>
+  - LintCode 575. 字符串解码 <https://www.lintcode.com/problem/decode-string/description>
+
 ## 数学
 
 - [阶乘后的零](src/math/factorial-trailing-zeroes.js)
diff --git a/src/stack/decode-string.js b/src/stack/decode-string.js
new file mode 100644
index 0000000..da36b31
--- /dev/null
+++ b/src/stack/decode-string.js
@@ -0,0 +1,36 @@
+// s = "3[a]2[bc]", 返回 "aaabcbc".
+// s = "3[a2[c]]", 返回 "accaccacc".
+// s = "2[abc]3[cd]ef", 返回 "abcabccdcdcdef".
+/**
+ * @param {string} s
+ * @return {string}
+ */
+export const decodeString = function (s) {
+  const stack = []
+  let multiple = ''
+  for (let i = 0, len = s.length; i < len; i++) {
+    if (!isNaN(Number(s[i]))) { // 判断是数字
+      if (i === 0 || !isNaN(Number(s[i - 1]))) { // 如果上一位也是数字，则
+        multiple += s[i]
+      } else {
+        multiple = s[i]
+      }
+    } else if (multiple && s[i] === '[') {
+      stack.push(Number(multiple))
+      multiple = ''
+    } else if (s[i] === ']') {
+      let current = stack.pop()
+      let tmpStr = ''
+      while (typeof current !== 'number') {
+        tmpStr = current + tmpStr
+        current = stack.pop()
+      }
+      tmpStr = tmpStr.repeat(current)
+      stack.push(tmpStr)
+    } else {
+      stack.push(s[i])
+    }
+  }
+
+  return stack.join('')
+}
diff --git a/test/stack/decode-string.test.js b/test/stack/decode-string.test.js
new file mode 100644
index 0000000..28a36eb
--- /dev/null
+++ b/test/stack/decode-string.test.js
@@ -0,0 +1,7 @@
+import { decodeString } from '../../src/stack/decode-string'
+
+test('字符串解码', () => {
+  expect(decodeString('3[a]2[bc]')).toBe('aaabcbc')
+  expect(decodeString('3[a2[c]]')).toBe('accaccacc')
+  expect(decodeString('2[abc]3[cd]ef')).toBe('abcabccdcdcdef')
+})