Buggy python submission (verdict: Runtime Error):
n = int(input())
ds = list(map(int, input().split()))

from collections import defaultdict
d = defaultdict(int)

d[0] = 1
for d_ in ds:
    d[d_] += 1
    if d_ == 12 and d[d_] == 2:
        print(0)
        exit()
    elif d_ == 0 and d[d_] == 2: 
        print(0)
        exit()
    elif d[d_] == 3:
        print(0)
        exit()

def calcmin(tmp):
    n = len(tmp)
    ret = 1 << 50
    for i in range(n):
        for j in range(i+1,n):
            ret = min(ret, abs(tmp[i]-tmp[j]))
    return ret

two = []
x = []
for k in d.keys():
    if d[k] == 2:
        two.append(k)
        two.append(24-k)
    if d[k] == 1:
        x.append(k)
two = list(set(two))
n = len(x)

ans = 0
for i in range(1 << n):
    tmp[] = x[:]
    for j in range(n):
        if i & (1 << j):
            tmp[j] = 24-x[j]
    tmp.extend(two)
    ans = max(calcmin(tmp), ans)
print(ans)

Fixed submission:
n = int(input())
ds = list(map(int, input().split()))

from collections import defaultdict
d = defaultdict(int)

d[0] += 1
for d_ in ds:
    d[d_] += 1
    if (d_ == 12 or d_ == 0) and d[d_] == 2:
        print(0)
        exit()
    elif d[d_] == 3:
        print(0)
        exit()

def calcmin(tmp):
    n = len(tmp)
    ret = 1 << 50
    for i in range(n):
        for j in range(i+1,n):
            ret = min(ret, abs(tmp[i]-tmp[j]),24-abs(tmp[i]-tmp[j]))
    return ret

two = []
x = []

for k in d.keys():
    if d[k] == 2 or k == 12:
        two.append(k)
        two.append(24-k)
    elif d[k] == 1:
        x.append(k)

two = list(set(two))
n = len(x)
ans = 0
for i in range(1 << n):
    tmp = x[:]
    for j in range(n):
        if i & (1 << j):
            tmp[j] = 24-x[j]
    # print(tmp,two)
    tmp.extend(two)
    ans = max(calcmin(tmp), ans)

print(ans)

Buggy python submission (verdict: Runtime Error):
n = int(input())
ds = list(map(int, input().split()))

from collections import defaultdict
d = defaultdict(int)

d[0] = 1
for d_ in ds:
    d[d_] += 1
    if d_ == 12 and d[d_] == 2:
        print(0)
        exit()
    elif d_ == 0 and d[d_] == 2: 
        print(0)
        exit()
    elif d[d_] == 3:
        print(0)
        exit()

def calcmin(tmp):
    n = len(tmp)
    ret = 1 << 50
    for i in range(n):
        for j in range(i+1,n):
            ret = min(ret, abs(tmp[i]-tmp[j]))
    return ret

two = []
x = []
for k in d.keys():
    if d[k] == 2:
        two.append(k)
        two.append(24-k)
    if d[k] == 1:
        x.append(k)
two = list(set(two))
n = len(x)

ans = 0
for i in range(1 << n):
    tmp[:] = x[:]
    for j in range(n):
        if i & (1 << j):
            tmp[j] = 24-x[j]
    tmp.extend(two)
    ans = max(calcmin(tmp), ans)
print(ans)

Fixed submission:
n = int(input())
ds = list(map(int, input().split()))

from collections import defaultdict
d = defaultdict(int)

d[0] += 1
for d_ in ds:
    d[d_] += 1
    if (d_ == 12 or d_ == 0) and d[d_] == 2:
        print(0)
        exit()
    elif d[d_] == 3:
        print(0)
        exit()

def calcmin(tmp):
    n = len(tmp)
    ret = 1 << 50
    for i in range(n):
        for j in range(i+1,n):
            ret = min(ret, abs(tmp[i]-tmp[j]),24-abs(tmp[i]-tmp[j]))
    return ret

two = []
x = []

for k in d.keys():
    if d[k] == 2 or k == 12:
        two.append(k)
        two.append(24-k)
    elif d[k] == 1:
        x.append(k)

two = list(set(two))
n = len(x)
ans = 0
for i in range(1 << n):
    tmp = x[:]
    for j in range(n):
        if i & (1 << j):
            tmp[j] = 24-x[j]
    # print(tmp,two)
    tmp.extend(two)
    ans = max(calcmin(tmp), ans)

print(ans)