水题，不说。
CO
/*
PROGRAM: $PROGRAM
AUTHOR: Su Jiao
DATE: 2010-3-19
DESCRIPTION:
$DESCRIPTION
*/
#include <iostream>
using std::cin;
using std::cout;
#include <fstream>
using std::ifstream;
using std::ofstream;
#include <sstream>
using std::stringstream;
using std::endl;
#include <vector>
using std::vector;
#include <string>
using std::string;
#include <stack>
using std::stack;
#include <queue>
using std::queue;
#include <map>
using std::map;
using std::pair;
using std::make_pair;
#include <algorithm>
using std::sort;
#include <cassert>
//using std::assert;
#include <cstdio>
//using std::EOF;
class Application
{
string file;
public:
Application()
{
char rc;
while ((rc=cin.get())!=EOF) file.push_back(rc);
}
int run()
{
bool comment=false;
int counter=0;
int last=~(1<<31);
bool answer=true;
for (int i=0;i<file.size();i++)
{
if (comment)
{
if (file[i]==’*’) last=i;
else if (file[i]==’)’&&last+1==i) comment=false;
}
else if (counter)
{
if (file[i]==’*’&&last+1==i)
{
counter–;
last=~(1<<31);
comment=true;
}
else if (file[i]==’)’)
{
counter–;
}
else if (file[i]=='(‘)
{
counter++;
last=i;
}
else
{
bool valid=false;
for (char* j=“=+-*/0123456789)(\n”;*j;j++)
if (file[i]==*j) valid=true;
if (!valid) answer=false;
}
}
else
{
if (file[i]=='(‘)
{
counter++;
last=i;
}
else if (file[i]==’)’)
{
answer=false;
}
}
}
if (comment||counter) answer=false;
cout<<(char*)(answer?“YES”:“NO”)<<endl;
return 0;
}
};
int main()
{
Application app;
return app.run();
}