Thread: Maze traversal in c

Well here is your code, nicely formatted.

Code:

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>

int main()
{
  // all variables declared
  int rows, columns, r, c, i, rowStart, columnStart, rowEnd, columnEnd, currentX, currentY;
  char **mazeblock;
  char orientation;
  FILE *fPointer;               // file pointer

  //read file into array
  fPointer = fopen("maze01.txt", "r");
  if (fPointer == NULL) {
    printf("Error in opening file\n");
    exit(1);                    // help check opening error
  }
  fscanf(fPointer, " %d %d %d %d %d %d \n", &rows, &columns, &rowStart, &columnStart, &rowEnd, &columnEnd);

  // Dynamically allocate memory
  mazeblock = (char **) malloc(sizeof(char *) * rows);

  // failure to allocate memory
  if (!mazeblock) {
    printf("memmory allocation failed");
  }

  for (i = 0; i < rows; i++) {
    mazeblock[i] = (char *) malloc(sizeof(char) * columns);
  }

  // to read in the maze
  for (r = 0; r < rows; r++) {
    for (c = 0; c < columns; c++) {
      fscanf(fPointer, "%c", &mazeblock[r][c]);
    }
  }
  fclose(fPointer);

  // Defining direction
  if (rowStart == 0) {
    orientation = 'S';
  } else if (rowStart == (rows - 1)) {
    orientation = 'N';
  } else if (columnStart == 0) {
    orientation = 'E';
  } else {
    orientation = 'W';
  }

  // to hold direction
  currentX = rowStart;
  currentY = columnStart;

  //
  // for going south rules
  while ((currentX != rowEnd) || (currentY != columnEnd)) {
    if (orientation == 'S') {
      if ((currentY > 0) && (mazeblock[currentX][currentY - 1] == ' ' || mazeblock[currentX][currentY - 1] == '#')) {
        mazeblock[currentX][currentY] = '#';
        --currentY;
        orientation = 'W';
      } else if ((currentX < (rows - 1))
                 && (mazeblock[currentX + 1][currentY] == ' ' || mazeblock[currentX + 1][currentY] == '#')) {
        mazeblock[currentX][currentY] = '#';
        ++currentX;
        orientation = 'S';
      } else if ((currentY < (columns - 1))
                 && (mazeblock[currentX][currentY + 1] == ' ' || mazeblock[currentX][currentY + 1] == '#')) {
        mazeblock[currentX][currentY] = '#';
        ++currentY;
        orientation = 'E';
      } else {
        mazeblock[currentX][currentY] = '#';
        --currentX;
        orientation = 'N';
      }
    }
    //for going North
    else if (orientation == 'N') {
      if ((currentY < (columns - 1))
          && (mazeblock[currentX][currentY + 1] == ' ' || mazeblock[currentX][currentY + 1] == '#')) {
        mazeblock[currentX][currentY] = '#';
        ++currentY;
        orientation = 'E';
      } else if ((currentX > 0)
                 && (mazeblock[currentX - 1][currentY] == ' ' || mazeblock[currentX - 1][currentY] == '#')) {
        mazeblock[currentX][currentY] = '#';
        --currentX;
        orientation = 'N';
      } else if ((currentY > 0)
                 && (mazeblock[currentX][currentY - 1] == ' ' || mazeblock[currentX][currentY - 1] == '#')) {
        mazeblock[currentX][currentY] = '#';
        --currentY;
        orientation = 'W';
      } else {
        mazeblock[currentX][currentY] = '#';
        currentX++;
        orientation = 'S';
      }
    }
    //for going West
    else if (orientation == 'W') {
      if ((currentX > 0) && (mazeblock[currentX - 1][currentY] == ' ' || mazeblock[currentX - 1][currentY] == '#')) {
        mazeblock[currentX][currentY] = '#';
        --currentX;
        orientation = 'N';
      } else if ((currentY > 0)
                 && (mazeblock[currentX][currentY - 1] == ' ' || mazeblock[currentX][currentY - 1] == '#')) {
        mazeblock[currentX][currentY] = '#';
        --currentY;
        orientation = 'W';
      } else if ((currentX < (rows - 1))
                 && (mazeblock[currentX + 1][currentY] == ' ' || mazeblock[currentX + 1][currentY] == '#')) {
        mazeblock[currentX][currentY] = '#';
        ++currentX;
        orientation = 'S';
      } else {
        mazeblock[currentX][currentY] = '#';
        currentY++;
        orientation = 'E';
      }
    }
    //For going east
    else {
      if ((currentX < (rows - 1))
          && (mazeblock[currentX + 1][currentY] == '0' || mazeblock[currentX + 1][currentY] == 'W')) {
        mazeblock[currentX][currentY] = 'W';
        ++currentX;
        orientation = 'S';
      } else if ((currentY < (columns - 1))
                 && (mazeblock[currentX][currentY + 1] == ' ' || mazeblock[currentX][currentY + 1] == '#')) {
        mazeblock[currentX][currentY] = '#';
        ++currentY;
        orientation = 'E';
      } else if ((currentX > 0)
                 && (mazeblock[currentX - 1][currentY] == ' ' || mazeblock[currentX - 1][currentY] == '#')) {
        mazeblock[currentX][currentY] = '#';
        --currentX;
        orientation = 'N';
      } else {
        mazeblock[currentX][currentY] = '#';
        currentY--;
        orientation = 'W';
      }
    }
  }

  mazeblock[currentX][currentY] = '# ';
  printf("\n");

  // output loop
  for (r = 0; r < rows; r++) {
    for (c = 0; c < columns; c++) {
      printf("%1c", mazeblock[r][c]);
    }
  }

  return 0;
}

The first problem is you don't even read in the maze properly.

> fscanf(fPointer, "%c", &mazeblock[r][c]);
This will fill your maze with \n characters from the input file.

> mazeblock[currentX][currentY] = '#';
Why are you filling in where you've been with the wall character?
If you reach a dead end, how are you going to get back to a place where you had a choice?

Add some constants to make the code more readable.

Code:

#define WALL '#'
#define FLOOR ' '
#define CRUMB '~' // mark where you've been
#define CHOICE '+' // a point in the maze where there was a choice of next move

So you can say things like

Code:

if ( maze[x][y] == FLOOR )
    maze[x][y] = CRUMB;