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Check-in [6538876b94]

Overview
Comment:202406 2nd star (not pretty)
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SHA3-256: 6538876b94409617762bcccf1812a9c95496dd764e90fdeaa5776c53195666bc
User & Date: nnz on 2024-12-06 16:28:38
Other Links: manifest | tags
Context
2024-12-06
16:32
202406 confirm 4 for repetitions check-in: fc7808669f user: nnz tags: trunk
16:28
202406 2nd star (not pretty) check-in: 6538876b94 user: nnz tags: trunk
13:54
add space for terminating zero check-in: 16cb8577e3 user: nnz tags: trunk
Changes
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Modified aoc2024.c from [02118ec5ef] to [4d7b1de895].

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            case 'X': row_pos += deltarow;
                      col_pos += deltacol;
                      break;
        }
    }
    printf("The guard visits %u positions before leaving the area.\n", visited);
    // Part Two
    unsigned rowblock = 0, colblock = 0, positions = 0;
    int row_initial = (int)(linear_pos / size);
    int col_initial = (int)(linear_pos % size);
    for (;;) {
        strcpy(data, savedmap);
        if (data[linearize2d(size, (unsigned)rowblock, (unsigned)colblock)] == '.') {
            data[linearize2d(size, (unsigned)rowblock, (unsigned)colblock)] = '#'; // block it
            row_pos = row_initial; col_pos = col_initial;
            deltarow = -1; deltacol = 0;
            data[linearize2d(size, (unsigned)row_pos, (unsigned)col_pos)] = '1';
            bool looping = false;
            while (!looping && validpos(size, row_pos + deltarow, col_pos + deltacol)) {
                switch (data[linearize2d(size, (unsigned)(row_pos+deltarow), (unsigned)(col_pos+deltacol))]) {
                    default: puts("stepped on default"); exit(EXIT_FAILURE);
                    case '#': if (data[linearize2d(size, (unsigned)(row_pos), (unsigned)(col_pos))] == '8') looping = true;
                              rightturn(&deltarow, &deltacol);
                              break;
                    case '8': looping = true; break;
                    case '.': data[linearize2d(size, (unsigned)(row_pos+deltarow), (unsigned)(col_pos+deltacol))] = '0';
                              /*fallthrough*/
                    case '1':
                    case '2':
                    case '3':
                    case '4':
                    case '5':
                    case '6':
                    case '7': data[linearize2d(size, (unsigned)(row_pos+deltarow), (unsigned)(col_pos+deltacol))]++;
                              row_pos += deltarow;
                              col_pos += deltacol;
                              break;
                }
            }
            if (looping) positions++;
        }
        colblock++;
        if (colblock == size) {
            colblock = 0;
            rowblock++;
            if (rowblock == size) break;
        }
    }
    printf("You can obstruct %u different positions.\n", positions);
    free(savedmap);
}

/* === aoc202405 =======================================================
===================================================================== */

static int ppcmp(unsigned a, unsigned b, unsigned (*r)[2], size_t nr) {
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