写一段代码，判断一个包括'{','[','(',')',']','}'的表达式是否合法(注意看样例的合法规则。) 给定一个表达式A,请返回一个bool值，代表它是否合法。

这道题比较奇怪，它的匹配规则并不是我们平时想想的那种匹配规则，例如：平时的匹配规则是()、{}、[]才能匹配，本题中(和} 、]、)都能匹配。所以做题时要好好审题。另外，本题中给的测试用例是错误的。

// ConsoleApplication5.cpp : 定义控制台应用程序的入口点。

//

#include "stdafx.h"
#include<vector>
#include<iostream>
#include<string>
#include <stack>
using namespace std;
class ChkExpression {
public:
	bool chkLegal(string A) {
		stack<char> inStack;
		stack<char> outStack;
		for (int i = 0; i < A.size(); i++)
		{
			inStack.push(A[i]);
		}
		while (!inStack.empty())
		{
			char ch = inStack.top();
			bool flag = true;
			cout << inStack.top() << "  ";
			if (!outStack.empty() )
			{
				cout << outStack.top() << endl;
			}
			else
			{
				cout << "空" << endl;
			}
			switch (ch)
			{
			case '}':
				outStack.push('}');
				inStack.pop();
				break;
			case ']':
				outStack.push(']');
				inStack.pop();
				break;
			case ')':
				outStack.push(')');
				inStack.pop();
				break;
			case '{':
				if (!outStack.empty() )
				{
					outStack.pop();
					inStack.pop();
				}
				else
				{
					flag = false;
				}
				break;
			case '[':
				if (!outStack.empty() )
				{
					outStack.pop();
					inStack.pop();
				}
				else
				{
					flag = false;
				}
				break;
				break;
			case '(':
				if (!outStack.empty() )
				{
					outStack.pop();
					inStack.pop();
				}
				else
				{
					flag = false;
				}
				break;
		/*	case '{':
				if (!outStack.empty() && outStack.top() == '}')
				{
					outStack.pop();
					inStack.pop();
				}
				else
				{
					flag = false;
				}
				break;
			case '[':
				if (!outStack.empty() && outStack.top() == ']')
				{
					outStack.pop();
					inStack.pop();
				}
				else
				{
					flag = false;
				}
				break;
			case '(':
				if (!outStack.empty() && outStack.top() == ')')
				{
					outStack.pop();
					inStack.pop();
				}
				else
				{
					flag = false;
				}
				break;*/
			default:
				inStack.pop();
				break;
			}
			if (flag == false)
			{
				break;
			}
		}
		if (outStack.empty() && inStack.empty())
		{
			return true;
		}
		else
		{
			return false;
		}
	}
};
int main()
{
	string A = "[a+b*(5-4)]*{x+b+b*(1+2)}";
	ChkExpression ce;
	cout << ce.chkLegal(A) << endl;
return 0;
}