ex9.c

ex9.c

#include <stdio.h>
#include <stdlib.h>
#define N_ROWS 5
#define N_COLS 5
void main(){
    char swamp[N_ROWS][N_COLS] = {
        {'*' , '*', '.', '*', '.' }, 
        {'.' , '.', '.', '.', '.' }, 
        {'.' , '.', '*', '.', '*' }, 
        {'.' , '*', '.', '*', '*' }, 
        {'*' , '.', '.', '.', '*' }
    };

    char steps[N_COLS - 1];
    int im_stuck;
    int r, c;
    int starting_row;

    im_stuck = 1;
     
    // for each starting position
    for(starting_row = 0; starting_row < N_ROWS; starting_row++){
        // we try to start moving from each position
        // the first time is the row number 0
        // if row 0 fails we try with row number 1 etc..
        printf("starting from row: %d\n", starting_row);

        // if we start in a bad position
        if(swamp[starting_row][0] == '.'){
            // skip this position and 
            // go to the next
            printf("blah im in the mud\n\n");
            continue;
        }
        
        // if im_stuck is still 0 when the for( int c .. loop finished 
        // then we didn't get stuck and reached the end of the swamp
        // so inside the steps[] array there is the solution
        if (im_stuck == 0){
            break;
        }
        // the program works when/if im_stuck doesn't change
        im_stuck = 0;

        // the first step is where we start from
        r = starting_row;

        // the columns steps to the right
        for(c = 0; c < (N_COLS - 1); c++){

            // printf("i'm at col %d\n", c);
            printf("i see:\n%c\n%c\n%c\n", swamp[r+1][c+1], swamp[r][c+1], swamp[r-1][c+1]); 

            // check if  there is a star on the square right-above
            // but also check that a right-below square exists
            if((r != N_ROWS ) && (swamp[r+1][c+1] == '*') ){
                printf("%d,%d is good\n", r+1, c+1);
                // the next row will be up
                r = r + 1;
                steps[c] = 'v';
            }
            // if there isnt a star on the square right-above
            // but there is a star in front of us
            else if(swamp[r][c+1] == '*'){
                printf("step right to (%d,%d)\n", r, c+1);
                // the next move will be on the same row
                r = r;
                steps[c] = '>';
            }
            // if there isnt a star on the square right-above or in front
            // but there is a star right-below
            else if((r != 0 ) && (swamp[r-1][c+1] == '*') ){
                printf("step up to (%d,%d)\n", r-1, c+1);
                // the next move will be down
                r = r - 1;
                steps[c] = '^';
            } else {
                // if there were no stars
                // we got stuck, and the program will try with another
                // starting position
                printf("stuck at (%d, %d)\n", r, c);
                // raise the IM STUCK flag
                im_stuck = 1;
                printf("path was: %s\n", steps);
                // go back to try starting in a different row
                break;
            }
        }
    }
    printf("a good path is:");
    printf("%d", starting_row - 1);
    printf("%s\n", steps);
}