[LeetCode]Valid Parentheses

最新推荐文章于 2019-07-31 23:36:17 发布

原创最新推荐文章于 2019-07-31 23:36:17 发布 · 1k 阅读

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

second time

class Solution {
public:
    bool matchBracket(char a, char b)
    {
        if(a == '[' && b == ']') return true;
        if(a == '(' && b == ')') return true;
        if(a == '{' && b == '}') return true;
        return false;
    }
    bool isValid(string s) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        stack<char> charStack;
        for(int i = 0; i < s.size(); ++i)
        {
            if(charStack.empty() || !matchBracket(charStack.top(), s[i])) charStack.push(s[i]);
            else charStack.pop();
        }
        
        return charStack.empty();
    }
};