4x5.c

#include <stdio.h>

void print_field(char field[4][6])
{
  int i;

  for (i = 0; i < 4; i++) {
    printf("%s\n", field[i]);
  }
}

void move_pos(char field[4][6], int x, int y, char *s)
{
  int new_x = x, new_y = y;
  char tmp;

  while (*s != '\0') {
    switch (*s) {
    case 'u': new_y--; break;
    case 'd': new_y++; break;
    case 'l': new_x--; break;
    case 'r': new_x++; break;
    }
    s++;
    if (new_x < 0 || new_x >= 5 || new_y < 0 || new_y >= 4) {
      continue;
    }
    tmp = field[y][x];
    field[y][x] = field[new_y][new_x];
    field[new_y][new_x] = tmp;
    x = new_x;
    y = new_y;
  }
}

int check_pos(int checker[4][5], int x, int y)
{
  if (checker[y][x] == 0) {
    checker[y][x] = 1;
    return 1;
  }
  return 0;
}

void mark_field(char field[4][6], int checker[4][5])
{
  int x, y;

  for (y = 0; y < 4; y++) {
    for (x = 0; x < 5; x++) {
      if (checker[y][x] != 0) {
        field[y][x] = '*';
      }
    }
  }
}

int test_field(char field[4][6])
{
  int checker[4][5] = {0};
  int count = 0;
  int x, y;

  for (x = 0; x < 3; x++) {
    for (y = 0; y < 4; y++) {
      if (field[y][x] == field[y][x + 1] && field[y][x] == field[y][x + 2]) {
        count += check_pos(checker, x, y)
          + check_pos(checker, x + 1, y)
          + check_pos(checker, x + 2, y);
      }
    }
  }

  for (x = 0; x < 5; x++) {
    for (y = 0; y < 2; y++) {
      if (field[y][x] == field[y + 1][x] && field[y][x] == field[y + 2][x]) {
        count += check_pos(checker, x, y)
          + check_pos(checker, x, y + 1)
          + check_pos(checker, x, y + 2);
      }
    }
  }

  printf("[Result]\n");
  mark_field(field, checker);
  print_field(field);

  if (count < 4 * 5) {
    printf("Not cleared\n");
    return 0;
  }

  printf("Cleared\n");
  return 1;
}

int main(int argc, char* argv[])
{
  char field[4][6] = {
    "aaacc",
    "abccc",
    "abccc",
    "bbbba"
  };

  printf("[1]\n");
  print_field(field);

  if (argc > 1) {
    move_pos(field, 4, 3, argv[1]);
    printf("[2]\n");
    print_field(field);
  }

  test_field(field);

  return 0;
}