C++ :

#include<iostream>
#include<cstring>
#include<cstdio>
using namespace std;
int n;
string s[25];
bool my_judge(string);
int change(char);
int main()
{
	//freopen("strs10.in","r",stdin);
	//freopen("strs10.out","w",stdout);
	cin>>n;
	for(int i=1;i<=n;++i)
	{
		cin>>s[i];
		//my_judge(s[i]);
		//cout<<s[i]<<endl;
		if(my_judge(s[i]))cout<<"YES"<<endl;
		else cout<<"NO"<<endl;
	}
}
bool my_judge(string s)
{
	int i=0,top=0,k;
	int a[300];
	memset(a,0,sizeof(a));
	a[0]=10;	
	//cout<<s<<endl;
	while(i<s.size())
	{
		k=change(s[i]);
		//cout<<s<<' '<<s[i]<<' '<<k<<endl;		
		if(top==0&&k==5)return false;
		if(k<5)
		{
			
			if(k>a[top])return false;
			else
			{
				++top;
				a[top]=k;
			}	
		}
		if(k==5)
		{
			if(s[i]=='>')
			{
				if(a[top]==1)top--;
				else return false;
			}
			if(s[i]==')')
			{
				if(a[top]==2)top--;
				else return false;
			}
			if(s[i]==']')
			{
				if(a[top]==3) top--;
				else return false;
			}
			if(s[i]=='}')
			{
				if(a[top]==4)top--;
				else return false;
			}
		}
		i++;		
	}
	//cout<<"y"<<endl;
	if(top==0)return true;
}
int change(char ch)
{
	if(ch=='<')return 1;
	if(ch=='(')return 2;
	if(ch=='[')return 3;
	if(ch=='{')return 4;
	return 5;
}

Pascal :

program acm21149;
var s:array[1..255] of longint;
    i,j,k,n,top,temp:longint;
    st:string;
    f:boolean;
function turn(c:char):longint;
begin
  case c of
    '<': turn:=1;
    '(': turn:=2;
    '[': turn:=3;
    '{': turn:=4;
    '>': turn:=-1;
    ')': turn:=-2;
    ']': turn:=-3;
    '}': turn:=-4;
  end;
end;
function check:boolean;
var i,j:longint;
begin
  check:=true;
  for i:=1 to top do
     if  s[i]<temp then
        exit(false);
end;
begin
  readln(n);
  for i:=1 to n do
    begin
      readln(st); top:=0; f:=true;
      for j:=1 to length(st) do
        begin
           temp:=turn(st[j]);
           if (temp>0) then
            if check then
             begin
               inc(top);
               s[top]:=temp;
             end
            else begin f:=false; break; end;
           if (temp<0) then
              if (top>0) and (s[top]+temp=0) then
               dec(top)
              else begin f:=false; break; end;
        end;
       if (top=0) and f then writeln('YES') else writeln('NO');
  end;
end.