Decompiled:

```C
#include "out.h"

int _init(EVP_PKEY_CTX *ctx)

{
int iVar1;

iVar1 = __gmon_start__();
return iVar1;
}

void FUN_00101020(void)

{
// WARNING: Treating indirect jump as call
(*(code *)(undefined *)0x0)();
return;
}

void FUN_00101050(void)

{
__cxa_finalize();
return;
}

void __stack_chk_fail(void)

{
// WARNING: Subroutine does not return
__stack_chk_fail();
}

// WARNING: Unknown calling convention -- yet parameter storage is locked

int putc(int __c,FILE *__stream)

{
int iVar1;

iVar1 = putc(__c,__stream);
return iVar1;
}

void processEntry _start(undefined8 param_1,undefined8 param_2)

{
undefined auStack_8 [8];

__libc_start_main(main,param_2,&stack0x00000008,0,0,param_1,auStack_8);
do {
// WARNING: Do nothing block with infinite loop
} while( true );
}

// WARNING: Removing unreachable block (ram,0x001010c3)
// WARNING: Removing unreachable block (ram,0x001010cf)

void deregister_tm_clones(void)

{
return;
}

// WARNING: Removing unreachable block (ram,0x00101104)
// WARNING: Removing unreachable block (ram,0x00101110)

void register_tm_clones(void)

{
return;
}

void __do_global_dtors_aux(void)

{
if (completed_0 != '\0') {
return;
}
FUN_00101050(__dso_handle);
deregister_tm_clones();
completed_0 = 1;
return;
}

void frame_dummy(void)

{
register_tm_clones();
return;
}

long super_optimized_calculation(int param_1)

{
long lVar1;
long lVar2;

if (param_1 == 0) {
lVar1 = 0;
}
else if (param_1 == 1) {
lVar1 = 1;
}
else {
lVar2 = super_optimized_calculation(param_1 + -1);
lVar1 = super_optimized_calculation(param_1 + -2);
lVar1 = lVar1 + lVar2;
}
return lVar1;
}

undefined8 main(void)

{
ulong uVar1;
long in_FS_OFFSET;
uint local_84;
uint local_78 [26];
long local_10;

local_10 = *(long *)(in_FS_OFFSET + 0x28);
local_78[0] = 0x8bf7;
local_78[1] = 0x8f;
local_78[2] = 0x425;
local_78[3] = 0x36d;
local_78[4] = 0x1c1928b;
local_78[5] = 0xe5;
local_78[6] = 0x70;
local_78[7] = 0x151;
local_78[8] = 0x425;
local_78[9] = 0x2f;
local_78[10] = 0x739f;
local_78[11] = 0x91;
local_78[12] = 0x7f;
local_78[13] = 0x42517;
local_78[14] = 0x7f;
local_78[15] = 0x161;
local_78[16] = 0xc1;
local_78[17] = 0xbf;
local_78[18] = 0x151;
local_78[19] = 0x425;
local_78[20] = 0xc1;
local_78[21] = 0x161;
local_78[22] = 0x10d;
local_78[23] = 0x1e7;
local_78[24] = 0xf5;
uVar1 = super_optimized_calculation(0x5a);
for (local_84 = 0; local_84 < 0x19; local_84 = local_84 + 1) {
putc((int)(uVar1 % (ulong)local_78[(int)local_84]),stdout);
}
putc(10,stdout);
if (local_10 != *(long *)(in_FS_OFFSET + 0x28)) {
// WARNING: Subroutine does not return
__stack_chk_fail();
}
return 0;
}

void _fini(void)

{
return;
}

```

The saved bytes in local_78 form the bytestring:

```
0x8bf70x8f0x4250x36d0x1c1928b0xe50x700x1510x4250x2f0x739f0x910x7f0x425170x7f0x1610xc10xbf0x1510x4250xc10x1610x10d0x1e70xf5
```

The core of the problem is
```
uVar1 = super_optimized_calculation(0x5a);
for (local_84 = 0; local_84 < 0x19; local_84 = local_84 + 1) {
putc((int)(uVar1 % (ulong)local_78[(int)local_84]),stdout);
}
```
The hex value '0x5a' (90: int)

The super optimized calculation:
```
long super_optimized_calculation(int param_1)

{
long lVar1;
long lVar2;

if (param_1 == 0) {
lVar1 = 0;
}
else if (param_1 == 1) {
lVar1 = 1;
}
else {
lVar2 = super_optimized_calculation(param_1 + -1);
lVar1 = super_optimized_calculation(param_1 + -2);
lVar1 = lVar1 + lVar2;
}
return lVar1;
}
```
We can write the same inefficient thing in python
```
def soc(a):
if a == 0:
return 0
elif a == 1:
return 1
else:
x = soc(a-1)
y = soc(a-2)
return x+y
```
Since this will take ages to compute we can optimize this with a cache:
```
cache = [0, 1, soc(2), soc(3), soc(4)]
def soc_opt(a):
if a < len(cache):
return cache[a]
else:
x = soc_opt(a-1)
y = soc_opt(a-2)
cache.append(x+y)
return cache[a]
```
We can check that it works by comparing the results of a manageable initial value:
```
>>>print(soc(12))
144
>>>print(soc_opt(12))
144
```
The desired initial value is 90, which computes to:
```
>>>print(soc_opt(90))
2880067194370816120
```

When combining the bytestring with the optimized computation result
```
n = soc_opt(90)

b = '0x8bf70x8f0x4250x36d0x1c1928b0xe50x700x1510x4250x2f0x739f0x910x7f0x425170x7f0x1610xc10xbf0x1510x4250xc10x1610x10d0x1e70xf5'
flag = ''
for x in b.split('0x'):
if x:
m = n % int(x, 16)
flag = f"{flag}{chr(m)}"
print(flag)
```
We get the flag:
```
bctf{what's_memoization?}
```