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July 1, 2008

Programming Challenges: Graphical Editor

Filed under: Blog — admin @ 1:31 am

PC/UVa IDs: 110105/10267, Popularity: B, Success rate: low, Level: 1

Few notes:

  • In the problem input, pixels are specified as [column# row#], whereas two-dimensional vectors (or arrays) are referenced using [row# column#] format.
  • The program would be doomed to infinite recursion if the condition on line #51 is omitted.

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#include <iostream>
#include <string>
#include <sstream>
#include <vector>
#include <iterator>
 
using namespace std;
 
typedef vector< vector< char > > twod_vector;
 
ostream& operator<<(ostream &out, const twod_vector &v)
{
	twod_vector::const_iterator p;
 
	for(p = v.begin(); p < v.end(); p++) {
		copy((*p).begin(), (*p).end(),
				ostream_iterator< char >(cout, ""));
		cout<<endl;
	}
 
	return out;
}
 
void reset(twod_vector &image)
{
	twod_vector::iterator p;
 
	for(p = image.begin(); p < image.end(); p++) {
		fill((*p).begin(), (*p).end(), 'O');
	}
}
 
void set_pixel(twod_vector &image, int x, int y, char c)
{
	image.at(y).at(x) = c;
}
 
void fill_rect(twod_vector &image,
		int x1, int y1, int x2, int y2, char c)
{
	for(int i = y1; i <= y2; i++) {
		for(int j = x1; j <= x2; j++) {
			image.at(i).at(j) = c;
		}
	}
}
 
void fill_region(twod_vector &image, int x, int y,
		char old_color, char new_color)
{
	if(old_color == new_color) {
		return;
	}
 
	image.at(y).at(x) = new_color;
 
	if(x > 0) {
		if(image.at(y).at(x - 1) == old_color) {
			fill_region(image, x - 1, y,
					old_color, new_color);
		}
	}
 
	if(x < static_cast<int>(image.at(y).size()) - 1) {
		if(image.at(y).at(x + 1) == old_color) {
			fill_region(image, x + 1, y,
					old_color, new_color);
		}
	}
 
	if(y > 0) {
		if(image.at(y - 1).at(x) == old_color) {
			fill_region(image, x, y - 1,
					old_color, new_color);
		}
	}
 
	if(y < static_cast<int>(image.size()) - 1) {
		if(image.at(y + 1).at(x) == old_color) {
			fill_region(image, x, y + 1,
					old_color, new_color);
		}
	}
}
 
void swap(int &x, int &y)
{
	int tmp = x;
	x = y;
	y = tmp;
}
 
int main(int argc, char *argv[])
{
	twod_vector image;
	string line;
 
	getline(cin, line);
	while(line[0] != 'X') {
		istringstream iss(line);
		int m, n, x, y, x1, x2, y1, y2;
		char command, c, file_name[13];
		twod_vector::iterator p;
 
		iss>>command;
		switch(command) {
		case 'I':
			iss>>m>>n;
 
			image.clear();
			image.resize(n);
			for(p = image.begin(); p < image.end(); p++) {
				(*p).resize(m);
			}
 
			reset(image);
 
			break;
		case 'C':
			reset(image);
 
			break;
		case 'L':
			iss>>x>>y>>c;
			x--;
			y--;
 
			set_pixel(image, x, y, c);
 
			break;
		case 'V':
			iss>>x>>y1>>y2>>c;
			x--;
			y1--;
			y2--;
 
			if(y1 > y2) {
				swap(y1, y2);
			}
 
			fill_rect(image, x, y1, x, y2, c);
 
			break;
		case 'H':
			iss>>x1>>x2>>y>>c;
			x1--;
			x2--;
			y--;
 
			if(x1 > x2) {
				swap(x1, x2);
			}
 
			fill_rect(image, x1, y, x2, y, c);
 
			break;
		case 'K':
			iss>>x1>>y1>>x2>>y2>>c;
			x1--;
			y1--;
			x2--;
			y2--;
 
			if(x1 > x2) {
				swap(x1, x2);
			}
			if(y1 > y2) {
				swap(y1, y2);
			}
 
			fill_rect(image, x1, y1, x2, y2, c);
 
			break;
		case 'F':
			iss>>x>>y>>c;
			x--;
			y--;
 
			fill_region(image, x, y,
					image.at(y).at(x), c);
 
			break;
		case 'S':
			iss.ignore();
			iss.getline(file_name, 13);
 
			cout<<file_name<<endl;
			cout<<image;
 
			break;
		}
 
		getline(cin, line);
	}
 
	return 0;
}
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4 Comments »

  1. hi

    i’m south korean, student.

    i was helped by your code. and i was impressed your fill_region method.

    thank you, i solved this problem with your post!

    (i’m sorry that i can’t speak english well…) …

    Comment by jhsieben — February 16, 2009 @ 9:44 am

  2. ID110105 Graphical Editor…

    Submission ID : 242861Verdict : SolvedRuntime : 0.088 secs.Language : CPP Problem() Graphical editors such as Photoshop allow us to alter bit-mapped images in the same way that text editors allow us to modify documents. Images are represented as an M x…

    Trackback by jhsieben programming alone — February 16, 2009 @ 9:48 am

  3. my code produces a run time error and i cannot trace it … i checked my fill() method and I do not use recursion .. still RTE .. hope u can help..
    //////////////////////////////////////////////////////////////////////////////////

    #include
    #include
    #include
    using namespace std;

    #define MAX 250
    #define I 1
    #define C 2
    #define L 3
    #define V 4
    #define H 5
    #define K 6
    #define F 7
    #define S 8
    #define X 0

    char table[MAX+1][MAX+1];
    int m=0,n=0;

    struct pixel{
    int r;
    int c;
    };
    vector split (string& s)
    {
    vector ret;
    int i = 0;
    while (i!= s.size())
    {
    //this is for ignoring multiple blanks
    while(i!= s.size() && isspace(s[i]))
    i++;
    //to find end of next word
    int j = i;
    while(j!= s.size() && !isspace(s[j]))
    j++;
    //if we find some non-wwhite space chars
    if (i!=j)
    {
    ret.push_back(s.substr(i,j-i));
    i=j;
    }
    }
    return ret;
    }

    void fill(int row,int column,char old,char cnew)
    {
    pixel p;
    p.r = row;
    p.c = column;
    table [p.r][p.c] = cnew;
    vector R;
    R.push_back(p);
    int i=0;
    while(i!=R.size())
    {
    row = R[i].r;column = R[i].c;
    if(column+1=0 && table[row][column-1]==old)
    {
    table[row][column-1]=cnew;
    p.r = row;p.c = column-1;
    R.push_back(p);
    //find(row,column-1,old,cnew);
    //call++;
    }
    if(row-1 >= 0 && table[row-1][column]==old)
    {
    table[row-1][column]=cnew;
    p.r = row-1;p.c = column;
    R.push_back(p);
    //find(row-1,column,old,cnew);
    //call++;
    }

    if( row+1 <m && table[row+1][column]==old)
    {
    table[row+1][column]=cnew;
    p.r = row+1;p.c = column;
    R.push_back(p);
    //find(row+1,column,old,cnew);
    //call++;
    }
    i++;
    }

    }
    void find (int row,int column,char old,char cnew)
    {
    //cout<<row<<” “<<column<<endl;

    if(column+1=0 && table[row][column-1]==old)
    {
    table[row][column-1]=cnew;
    find(row,column-1,old,cnew);
    //call++;
    }
    if(row-1 >= 0 && table[row-1][column]==old)
    {
    table[row-1][column]=cnew;
    find(row-1,column,old,cnew);
    //call++;
    }

    if( row+1 <n && table[row+1][column]==old)
    {
    table[row+1][column]=cnew;
    find(row+1,column,old,cnew);
    //call++;
    }

    else
    {
    //r=row;
    //c=column;
    return;
    }
    }

    bool execute(string params)
    {
    //cout<<params<<endl;
    vector p = split(params);
    //for(int i=0;i<p.size();i++)
    // cout<<p[i]<<” “;
    //printf(“%d %d %d”,p[0],p[1],p[2]);
    switch(p[0].at(0))
    {
    case ‘I': {char s[10];int i;
    //copying
    for(i=0;i<p[1].size();i++) s[i] = p[1][i];s[i] = ”;n = atoi(s);
    for(i=0;i<p[2].size();i++) s[i] = p[2][i];s[i] = ”;m = atoi(s);
    //printf(“m%d n%d\n”,m,n);
    //colouring white
    for(int i=0;i<m;i++)
    { for(int j=0;j<n;j++) table[i][j] = ‘O'; }
    return true;
    }
    case ‘C':{for(int i=0;i<m;i++)
    {for(int j=0;j<n;j++) table[i][j] = ‘O'; }}
    break;
    case ‘L': {char s[10];int x,y;char ch;int i;
    for(i=0;i<p[1].size();i++) s[i] = p[1][i];s[i] = ”;x = atoi(s)-1;
    for(i=0;i<p[2].size();i++) s[i] = p[2][i];s[i] = ”;y = atoi(s)-1;
    if(xn || ym)
    return true;
    ch = p[3].at(0);
    table[y][x] = ch;}
    break;
    case ‘V': {char s[10];int x,y1,y2; char ch;int i;
    for(i=0;i<p[1].size();i++) s[i] = p[1][i];s[i] = ”;x = atoi(s)-1;
    for(i=0;i<p[2].size();i++) s[i] = p[2][i];s[i] = ”;y1 = atoi(s)-1;
    for(i=0;i<p[3].size();i++) s[i] = p[3][i];s[i] = ”;y2 = atoi(s)-1;
    ch = p[4].at(0);
    if(xn || y1m || y2m)
    return true;
    int y = min(y1,y2);
    int h = max(y1,y2);
    for(;y<=h;y++) table[y][x] = ch;}
    break;
    case ‘H': {char s[10];int x1,x2,y; char ch;int i;
    for(i=0;i<p[1].size();i++) s[i] = p[1][i];s[i] = ”;x1 = atoi(s)-1;
    for(i=0;i<p[2].size();i++) s[i] = p[2][i];s[i] = ”;x2 = atoi(s)-1;
    for(i=0;i<p[3].size();i++) s[i] = p[3][i];s[i] = ”;y = atoi(s)-1;
    ch = p[4].at(0);
    if(x1n || x2n || ym)
    return true;
    int x = min(x1,x2);
    int h = max(x1,x2);
    for(;x<=h;x++) table[y][x] = ch;}
    break;
    case ‘K': {char s[10];int x1,x2,y1,y2; char ch;int i;
    for(i=0;i<p[1].size();i++) s[i] = p[1][i];s[i] = ”;x1 = atoi(s)-1;
    for(i=0;i<p[2].size();i++) s[i] = p[2][i];s[i] = ”;y1 = atoi(s)-1;
    for(i=0;i<p[3].size();i++) s[i] = p[3][i];s[i] = ”;x2 = atoi(s)-1;
    for(i=0;i<p[4].size();i++) s[i] = p[4][i];s[i] = ”;y2 = atoi(s)-1;
    ch = p[5].at(0);
    if(x1n || x2n || y1m || y2m)
    return true;
    for(int y = min(y1,y2);y<=max(y1,y2);y++){for(int x=min(x1,x2);x<=max(x1,x2);x++) table[y][x] = ch;}}
    break;
    case ‘F':{char s[10];int x,y;char ch;int i;
    for(i=0;i<p[1].size();i++) s[i] = p[1][i];s[i] = ”;x = atoi(s)-1;
    for(i=0;i<p[2].size();i++) s[i] = p[2][i];s[i] = ”;y = atoi(s)-1;
    ch = p[3][0];
    if(xn || ym)
    return true;
    fill(y,x,table[y][x],ch);
    }
    break;
    case ‘S':{string name = p[1];
    cout<<name<<endl;
    for(int i=0;i<m;i++)
    {
    for(int j=0;j<n;j++)
    printf(“%c”,table[i][j]);
    cout<<endl;
    }}
    break;
    case ‘X':return false;
    default:return true;
    }
    return true;
    }

    int main()
    {
    string s;
    getline(cin,s);
    while(s == “”)
    getline(cin,s);

    while(execute(s) )
    {
    getline(cin,s);
    while(s == “”)
    getline(cin,s);
    }
    //vector ans = split(s);
    //execute(I,s);
    //cout<<“answern size”<<ans.size();
    //for(int i=0;i<ans.size();i++)cout<<ans[i]<<endl;
    return 0;
    }

    Comment by Mohit — April 13, 2009 @ 11:41 pm

  4. Hi there,

    how do you manage to look for errors in your code? On wrong submissions no hints or failed test cases will be desplayed at the programming-challenge site nor uva online judge.

    Comment by svn-kmf — January 19, 2012 @ 11:38 pm

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