Question

The programming language has to be C

The user is going to provide you with a map of rivers and grassland. Each cell on the map will be either grassland or river. Your job is to decorate this map with forks, 4 way forks, and river bends when a river bends. You will process the user's map and modify the river cells if they depict a river bend.

You will use enums to model the river, its bends, and forks. You will pattern match to replace parts of the river with bends and forks. Out of bounds regions will be considered grasslands for pattern matching simplicity.

You will use enums in this program.

You will print the integers with 1 space padding and rows will be terminated by new lines:

10 10 10
 1  2  3
 4  5  6
 7  8  9
10 10 10

Input and Output

The tiles that we use in the map are:

• 0 Grassland
• 1 River
• 2 NorthWestRiverBend
• 3 SouthWestRiverBend
• 4 NorthEastRiverBend
• 5 SouthEastRiverBend
• 6 NorthEastSouthFork
• 7 NorthWestSouthFork
• 8 WestNorthEastFork
• 9 WestSouthEastFork
• 10 FourWayFork

The user will input maps usually of 0 and 1 but they can include other tiles as well. Typically it will 0 and 1.

The user will input a map of

P2
6 7
10
 0  0  0  0  0  0 
 0  1  1  1  1  0
 0  1  0  0  1  0 
 0  1  1  1  1  1
 0  1  0  0  1  0
 0  1  1  1  1  0
 0  0  0  0  1  0

Where 0 is grassland and 1 is river

The program will look for corners and replace them with the RiverBend pieces.

P2
6 7
10
 0  0  0  0  0  0 
 0  5  1  1  3  0 
 0  1  0  0  1  0 
 0  6  1  1 10  1 
 0  1  0  0  1  0 
 0  4  1  1  7  0 
 0  0  0  0  1  0 

The header format is described below. $WIDTH is the number of cells wide and $HEIGHT is the number of cells tall.

P2
$WIDTH $HEIGHT
10

The individual cells are whitespace seperated for input. Ignore whitespace and newlines for the cells.

The output format is strict, each row ends in a newline and there is 1 space padding for all integers cells printed.

Please review the q1a-test?-input.txt files for more examples

Patterns

• Examples of No change

 0  0  0         0  0  0
 0  0  0    ->   0  0  0
 0  0  0         0  0  0
 
 0  0  0         0  0  0
 0  0  0    ->   0  0  0
 0  0  1         0  0  1
  
 0  0  0         0  0  0
 0  0  0    ->   0  0  0
 1  1  1         1  1  1
 

These examples are in cross form, this means that the corners can be anything (river or grassland). This is only 1 cell being changed, you are expected to apply these patterns to all cells.

• 2 NorthWestRiverBend

    1               1   
 1  1  0    ->   1  2  0
    0               0   

For example:

 0  1  0         0  1  0
 1  1  0    ->   1  2  0
 0  0  0         0  0  0

• 3 SouthWestRiverBend

    0               0   
 1  1  0    ->   1  3  0
    1               1

For example:

 1  0  1         1  0  1
 1  1  0    ->   1  3  0
 1  1  1         1  1  1

• 4 NorthEastRiverBend

    1               1   
 0  1  1    ->   0  4  1
    0               0  

• 5 SouthEastRiverBend

    0               0  
 0  1  1    ->   0  5  1
    1               1  

• 6 NorthEastSouthFork

    1               1   
 0  1  1    ->   0  6  1
    1               1  

• 7 NorthWestSouthFork

    1               1   
 1  1  0    ->   1  7  0
    1               1   

• 8 WestNorthEastFork

    1               1   
 1  1  1    ->   1  8  1
    0               0   

• 9 WestSouthEastFork

    0               0  
 1  1  1    ->   1  9  1
    1               1  

• 10 FourWayFork

    1               1  
 1  1  1    ->   1 10  1
    1               1  

More details

Maximum supported dimension in width or height is 16000

The format you input and output is called plain PGM. PGM is portable grey map format so you can use some image programs to view it.

Invalid input (including unexpected EOF) should be aborted immediately with the message:

Invalid input!

Hints

• Initialize your memory when you malloc it
• Remember to check the bounds of the array.
• You should make/extract a cursor so you can pattern match.
• You should consider writing unit tests for the patterns
• You should consider creating new arrays dynamically where need be.
• Return appropriate values from the functions to avoid segmentation faults.
• If you find any task repetitive, make it a function.
• You should read from 1 2D array and write to another.
• You can visualize your output better if you pipe your program through utfdraw.sh (you need GNU sed)

Answer 1

Screenshot of the code

Below is the c code for the same. The code reads input from the file input.txt and writes output to console as well as file output.txt . Enum has been used to represent grassland,river,river-bends & forks.

#include<stdio.h>

#include<stdlib.h>

#define MAX_DIMENSION 16000// defining maximum dimension

//enum for tiles

enum tiles{Grassland,River,NorthWestRiverBend,SouthWestRiverBend,

NorthEastRiverBend,SouthEastRiverBend,

NorthEastSouthFork,NorthWestSouthFork,

WestNorthEastFork,WestSouthEastFork,FourWayFork};

//function for decorating map

void decorate_map(int **map,int width, int height){

//checking patterns in map

for(int i=0;i<height;i++){

for(int j=0;j<width;j++){

if(map[i][j]==0)

continue;

if(i>0&&j>0&&i<height-1&&j<height-1&&map[i-1][j]==1&&map[i+1][j]==1&&map[i][j-1]==1&&map[i][j+1]==1)

map[i][j]=FourWayFork;

else if(j>0&&i<height-1&&j<height-1&&map[i+1][j]==1&&map[i][j-1]==1&&map[i][j+1]==1)

map[i][j]=WestSouthEastFork;

else if(i>0&&j>0&&j<height-1&&map[i-1][j]==1&&map[i][j-1]==1&&map[i][j+1]==1)

map[i][j]=WestNorthEastFork;

else if(i>0&&j>0&&i<height-1&&map[i-1][j]==1&&map[i+1][j]==1&&map[i][j-1]==1)

map[i][j]=NorthWestSouthFork;

else if(i>0&&i<height-1&&j<height-1&&map[i-1][j]==1&&map[i+1][j]==1&&map[i][j+1]==1)

map[i][j]=NorthEastSouthFork;

else if(i<height-1&&j<height-1&&map[i+1][j]==1&&map[i][j+1]==1)

map[i][j]=SouthEastRiverBend;

else if(i>0&&j<height-1&&map[i-1][j]==1&&map[i][j+1]==1)

map[i][j]=NorthEastRiverBend;

else if(j>0&&i<height-1&&map[i+1][j]==1&&map[i][j-1]==1)

map[i][j]=SouthWestRiverBend;

else if(i>0&&j>0&&map[i-1][j]==1&&map[i][j-1]==1)

map[i][j]=NorthWestRiverBend;

}

}

}

int main(){

FILE *fp;

fp=fopen("input.txt","r");//input file

FILE *fp2;

fp2=fopen("output.txt","w");//output file

char P2[3];

if(!(fgets(P2,3,fp)))//inputting first line

printf("Invalid input!");

printf("%s\n",P2);

fprintf(fp2,"%s\n",P2);

int width,height;

if(!(fscanf(fp,"%d",&width)&&fscanf(fp,"%d",&height)))//inputting width and height

printf("Invalid input!");

printf("%d %d\n",width,height);

fprintf(fp2,"%d %d\n",width,height);

int _10_;

if(!(fscanf(fp,"%d",&_10_)))

printf("Invalid input!");

printf("%d\n",_10_);

fprintf(fp2,"%d\n",_10_);

//declaring map of max dimensions

int ** map;

map=(int **)malloc(sizeof(int*)*MAX_DIMENSION);

for(int i=0;i<MAX_DIMENSION;i++)

map[i]=(int *)malloc(sizeof(int)*MAX_DIMENSION);

//inputting map

for(int i=0;i<height;i++)

for(int j=0;j<width;j++)

if(!(fscanf(fp,"%d",&map[i][j])))

printf("Invalid input!");

//calling function to decorate map

decorate_map(map,width,height);

//outputting map

for(int i=0;i<height;i++){

for(int j=0;j<width;j++){

printf("%d ",map[i][j]);

fprintf(fp2,"%d ",map[i][j]);

}

printf("\n");

fprintf(fp2,"\n");

}

//freeing memory

for(int i=0;i<MAX_DIMENSION;i++)

free(map[i]);

free(map);

}