[LeetCode] Valid Parentheses 解题报告

最新推荐文章于 2020-06-06 04:06:51 发布

原创最新推荐文章于 2020-06-06 04:06:51 发布 · 209 阅读

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本文介绍了一种使用栈数据结构来验证包含括号的字符串是否有效的算法。通过遍历输入字符串，遇到左括号将其压入栈中，遇到右括号则检查栈顶元素是否为对应的左括号。最后检查栈是否为空以确定字符串的有效性。

Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.

The brackets must close in the correct order, "()" and "()[]{}" are all valid but "(]" and "([)]" are not.

» Solve this problem

[解题思路]
经典的栈匹配。一个栈，左符号入栈，右符号出栈。最后检查栈是否为空。

[Code]

1:    bool isValid(string s) {  
2:      // Start typing your C/C++ solution below  
3:      // DO NOT write int main() function  
4:      vector<char> sta;  
5:      if(s.size() ==0) return false;  
6:      sta.push_back(s[0]);  
7:      for(int i =1; i< s.size(); i++)  
8:      {  
9:        if(s[i] == '(' || s[i] == '[' || s[i] == '{')  
10:        {  
11:          sta.push_back(s[i]);  
12:          continue;  
13:        }  
14:        char current = sta.back();  
15:        if(s[i] == ')' && current != '(')  
16:          return false;  
17:        if(s[i] == ']' && current != '[')  
18:          return false;  
19:        if(s[i] == '}' && current != '{')  
20:          return false;  
21:        sta.pop_back();  
22:      }  
23:      if(sta.size() !=0) return false;  
24:      return true;  
25:    }