LeetCode——Valid Parentheses

最新推荐文章于 2025-08-08 11:49:43 发布

pickless

最新推荐文章于 2025-08-08 11:49:43 发布

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分类专栏： Online Judge 文章标签： leetcode

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本文介绍了一个使用堆栈数据结构来验证括号是否正确配对的算法。通过遍历字符串并利用堆栈记录左括号的方式，可以高效地检查括号序列的有效性。

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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

经典的堆栈（stack）例子。

class Solution {
public:
    bool isValid(string s) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        stack<char> stacks;
        for (int i = 0; i < s.size(); i++) {
            switch (s[i]) {
                case '(':
                case '[':
                case '{':
                    stacks.push(s[i]);
                    break;
                case ')':
                    if (stacks.empty() || stacks.top() != '(') {
                        return false;
                    }
                    stacks.pop();
                    break;
                case ']':
                    if (stacks.empty() || stacks.top() != '[') {
                        return false;
                    }
                    stacks.pop();
                    break;
                case '}':
                    if (stacks.empty() || stacks.top() != '{') {
                        return false;
                    }
                    stacks.pop();
                    break;
                default:
                    return false;
            }
        }
        return stacks.empty();
    }
};