49_leetcode_Longest Valid Parentheses

Given a string containing just the characters '(' and ')', find the length of the longest valid (well-formed) parentheses substring.

For "(()", the longest valid parentheses substring is "()", which has length = 2.

Another example is ")()())", where the longest valid parentheses substring is "()()", which has length = 4.

1:注意特殊情况；2:new一个bool数组，3:对字符串中的字符进行进栈和出栈操作，并且初始相应的bool数组；4:统计bool数组中连续true的个数

    int longestValidParentheses(string s)
    {
        if(s.size() <= 1)
        {
            return 0;
        }
        
        stack<int> myStack;
        int size = (int)s.size();
        bool* flag = new bool[size] ;
        memset(flag, false, size);
        
        for(int i = 0; s[i] != '\0'; i++)
        {
            if(s[i] == '(')
            {
                myStack.push(i);
            }
            else
            {
                if(!myStack.empty() && s[myStack.top()] == '(')
                {
                    flag[myStack.top()] = true;
                    myStack.pop();
                    flag[i] = true;
                }
            }
        }
        
        int maxNumber = 0;
        int count = 0;
        for(int i = 0; i < size; i++)
        {
            if(flag[i] == true)
            {
                count++;
                if(count > maxNumber)
                {
                    maxNumber = count;
                }
            }
            else
            {
                count = 0;
            }
        }
        
        
        delete []flag;
        return maxNumber;
    }