LC Display这道题害我到一点才睡

http://acm.jlu.edu.cn/joj/showproblem.php?pid=1025
老是Presentation Error,无语了！

#include<iostream>
#include<string>
using namespace std;
//Horizonal state:
//0: skip; 1: '-' required
//Vertical state:
//0: skip; 1: single right '|'
//2: single left '|' 3:both lines

const int lcDisplayData[10][5] = {
	{1,3,0,3,1},//0 five rows 
	{0,1,0,1,0},//1
	{1,1,1,2,1},//2
	{1,1,1,1,1},//3
	{0,3,1,1,0},//4
	{1,2,1,1,1},//5
	{1,2,1,3,1},//6
	{1,1,0,1,0},//7
	{1,3,1,3,1},//8
	{1,3,1,1,1}//9
};
//H represent Horizonal
//V represent Vertical
//D represent Done
char cdStates[] = {
	'H','V','H','V','H','D'
};

string horizonal_segment(int type,int sz){
	int i = 0;
	string segment = "";
	segment.push_back(' ');
	switch(type){
		case 1:
			for(i = 0; i < sz; i++)
				segment.push_back('-');	
			break;
		case 0:
			for(i = 0; i < sz; i++)
				segment.push_back(' ');
			break;
		default:
			break;
	}
	segment.push_back(' ');
	segment.push_back(' ');//blank between digit
	return segment;
}

string vertical_segment(int type, int sz){
	string segment = "";
	int i;
	switch(type){
		case 1:
			segment.push_back(' ');
			for(i = 0; i < sz; i++)
				segment.push_back(' ');
			segment.push_back('|');
			break;
		case 2:
			segment.push_back('|');
			for(i = 0; i < sz; i++)
				segment.push_back(' ');
			segment.push_back(' ');
			break;
		case 3:
			segment.push_back('|');
			for(i = 0; i < sz; i++)
				segment.push_back(' ');
			segment.push_back('|');
			break;
		default:
			segment.push_back(' ');
			for(i = 0; i < sz; i++)
				segment.push_back(' ');
			segment.push_back(' ');
			break;
	}
	segment.push_back(' ');//blank between digit
	return segment;
}

void display(int size,string num){
	int i,j,k;
	for(i = 0; i < 6; i++){
		string line = "";
		switch(cdStates[i]){
			case 'H':
				for(j = 0; j < num.length(); j++){
					line.append( horizonal_segment(lcDisplayData[ num[j]-'0' ][i],size) );
				}
				cout << line.substr(0,line.length()-1) << endl;//use substr remove last ' '
				break;
			case 'V':
				for(k = 0; k < size; k++){
					line = "";
					for(j = 0; j < num.length(); j++){
						line.append(vertical_segment(lcDisplayData[ num[j]-'0' ][i],size));
					}
					cout << line.substr(0,line.length()-1) << endl;
				}
				break;
			case 'D':
				break;
		}
	}
}

int main(){
	int size;
	string num;
	int flag = 0;
	while(cin >> size >> num){
		if(flag)
			cout << endl;
		else
			flag = 1;
		display(size,num);	
	}
}