FOJ2030(DFS:括号匹配)

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#include < iostream >
using namespace std;
char ch[ 101 ];
int mark = 0 , cnt;
int len;
void dfs( int x , int y , int i )
{
if ( x < y )
{ return ; }
if ( y == x && i == len )
{
cnt ++ ;
}

if (ch[i] == ' ? ' )
{
dfs(x + 1 , y , i + 1 );
dfs(x, y + 1 , i + 1 );
}

if (ch[i] == ' ( ' )
{

dfs( x + 1 , y , i + 1 );

}

if (ch[i] == ' ) ' )
{
dfs( x , y + 1 , i + 1 );
}

}
int main()
{
while (cin >> ch)
{
cnt = 0 ; len = strlen( ch );
dfs( 0 , 0 , 0 );

if (mark == 1 ) cout << " 0 " << endl;

else cout << cnt << endl;
}
return 0 ;

}