GFSJ0186-【notsequence】

int main()
{
  _DWORD *v0; // eax
  int v2; // [esp+14h] [ebp-Ch]
  _DWORD *v3; // [esp+1Ch] [ebp-4h]

  memset(&unk_8049BE0, 0, 0x4000u);
  puts("input raw_flag please:");
  v3 = &unk_8049BE0;
  do
  {
    v0 = v3++;
    scanf("%d", v0);
  }
  while ( *(v3 - 1) );
  v2 = sub_80486CD(&unk_8049BE0);
  if ( v2 == -1 )
  {
    printf("check1 not pass");
    system("pause");
  }
  if ( (unsigned __int8)sub_8048783(&unk_8049BE0, v2) != 1 )
  {
    printf("check2 not pass!");
    exit(0);
  }
  if ( v2 == 20 )
  {
    puts("Congratulations! fl4g is :\nRCTF{md5(/*what you input without space or \\n~*/)}");
    exit(0);
  }
  return 0;
}

int __cdecl sub_80486CD(int a1)
{
  int j; // [esp+0h] [ebp-14h]
  int v3; // [esp+4h] [ebp-10h]
  int i; // [esp+8h] [ebp-Ch]
  int v5; // [esp+Ch] [ebp-8h]

  v5 = 0;
  for ( i = 0; i <= 1024 && *(_DWORD *)(4 * i + a1); i = v5 * (v5 + 1) / 2 )
  {
    v3 = 0;
    for ( j = 0; j <= v5; ++j )
      v3 += *(_DWORD *)(4 * (j + i) + a1);
    if ( 1 << v5 != v3 )
      return -1;
    ++v5;
  }
  return v5;
}

int __cdecl sub_8048783(int a1, int a2)
{
  int v3; // [esp+10h] [ebp-10h]
  int v4; // [esp+14h] [ebp-Ch]
  int i; // [esp+18h] [ebp-8h]
  int v6; // [esp+1Ch] [ebp-4h]

  v6 = 0;
  for ( i = 1; i < a2; ++i )
  {
    v4 = 0;
    v3 = i - 1;
    if ( !*(_DWORD *)(4 * i + a1) )
      return 0;
    while ( a2 - 1 > v3 )
    {
      v4 += *(_DWORD *)(4 * (v3 * (v3 + 1) / 2 + v6) + a1);
      ++v3;
    }
    if ( *(_DWORD *)(4 * (v3 * (v3 + 1) / 2 + i) + a1) != v4 )
      return 0;
    ++v6;
  }
  return 1;
}

import hashlib
import math

nums = []

for n in range(20):
    for k in range(n + 1):
        nums.append(math.comb(n, k))

s = "".join(map(str, nums))

print("RCTF{" + hashlib.md5(s.encode()).hexdigest() + "}")

RCTF{37894beff1c632010dd6d524aa9604db}