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🐱(stack): 394. 字符串解码

Python 栈版本优化

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Original file line number	Diff line number	Diff line change
`@@ -991,6 +991,38 @@ class Solution:`
`991`	`991`	`return ''.join(stack)`
`992`	`992`	```
`993`	`993`
	`994`	`+优化:`
	`995`	`+`
	`996`	+1. 将数字记录在 `multi` 中,字母记录在 `res` 中
	`997`	+2. 遇到 `[` 时,将 `[multi, res]` 入栈,并重置 `multi` 和 `res`
	`998`	+3. 遇到 `]` 时,从栈顶取元素 `[num, string]`,并计算 `res = string + num * res`
	`999`	`+`
	`1000`	+```python
	`1001`	`+class Solution:`
	`1002`	`+ def decodeString(self, s: str) -> str:`
	`1003`	`+ stack = []`
	`1004`	`+ # 存放字符串和数字`
	`1005`	`+ res, multi = '', 0`
	`1006`	`+ # ans = ''`
	`1007`	`+ for c in s:`
	`1008`	`+ if c == '[':`
	`1009`	`+ # 已经统计的 res 和 multi 入栈`
	`1010`	`+ stack.append([res, multi])`
	`1011`	`+ res, multi = '', 0`
	`1012`	`+ elif c == ']':`
	`1013`	`+ # 出栈并计算结果`
	`1014`	`+ string, num = stack.pop()`
	`1015`	`+ res = string + res * num`
	`1016`	`+ elif '0' <= c and c <= '9':`
	`1017`	`+ # 记录数字`
	`1018`	`+ multi = 10 * multi + int(c)`
	`1019`	`+ else:`
	`1020`	`+ # 遇到字母`
	`1021`	`+ res += c`
	`1022`	`+ # print(stack)`
	`1023`	`+ return res`
	`1024`	+```
	`1025`	`+`
`994`	`1026`	`## 503. 下一个更大元素 II`
`995`	`1027`
`996`	`1028`	`[原题链接](https://leetcode-cn.com/problems/next-greater-element-ii/submissions/)`

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