NCCU Assignment 4: Modified "hopscotch" game

hopscotch.c

#include <stdio.h>
#include <stdlib.h>
#define DATA_SIZE_LIMIT 30

#
# how to compile and execute:
# gcc hopscotch.c -o hopscotch
# ./hopscotch < input.txt
#

int n = 0, answer, step_limit;

typedef struct 
{
  int data[DATA_SIZE_LIMIT];
  int size; // init at 0
} List;

void printList(List list)
{
  if(list.size - 1 < 0)
  {
    printf("emtpy");
  }
  for (int i = 0; i < list.size; i += 1)
  {
    printf("%d", list.data[i]);
  }
  printf("\n");
}

void init(List *list, int a) {
  for (int i = 0; i < list->size; i += 1) {
    list->data[i] = a;
  }
}

void append(List *list, int a)
{
  list->data[list->size] = a;
  list->size += 1;
}

void copyList(List *new_list, List list)
{
  new_list->size = list.size;
  for (int i = 0; i < list.size; i += 1)
  {
    new_list->data[i] = list.data[i];
  }
}

int isDec(List list) {
  for (int i = list.size - 1; i >= 1; i -= 1) { //只能到倒數第二個
    if(list.data[i] < list.data[i - 1]) {
      return 0;
    }
  }
  return 1;
}

void walk(int n, List list)
{
  if (n < 0){
    return;
  }
  if (n == 0)
  {
    if(isDec(list) && list.size <= step_limit)
    {
      // printList(list);
      answer += 1;
    }
    return;
  }
  for (int i = 1; i < 5; i += 1)
  {
    List new_list;
    init(&new_list, 0);
    copyList(&new_list, list);
    append(&new_list, i);
    walk(n - i, new_list);
  }
}

int main()
{
  while(scanf("%d\n", &n) == 1) {
    List list;
    init(&list, 0);
    step_limit = (n - 1) / 10 * 10 + 7;
    answer = 0;
    walk(n, list);
    printf("%d\n", answer);
  }
  return 0;
}

input.txt

5
8
10
15

Below are the important rules during the jumping:

1. The player never quits.
2. The player never goes back.
3. The player never jumps out-of-bounds.
4. The player always randomly jumps 1, 2, 3 or 4 position(s) once at a time.
5. The player always starts from the start position.
6. If the specific position is 1 ~ 10, then the most jumps the player can jump is 7.
   If the specific position is 11 ~ 20, then the most jumps the player can jump is 17.
   If the specific position is 21 ~ 30, then the most jumps the player can jump is 27.

Input Format

There are several lines within the input file, each of which represents the position number n that the player would like to jump to. Those numbers are between 4 and 30. (i.e., 3 < n < 31).