Problem p02756 (python)

Fixed submission:
import sys
import math
from decimal import Decimal, ROUND_HALF_UP, ROUND_HALF_EVEN
from collections import deque
from bisect import bisect_left
from itertools import product
def I(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LI2(N): return [list(map(int, sys.stdin.readline().split())) for i in range(N)]
def LSI(): return list(map(int, list(sys.stdin.readline().rstrip())))
def LSI2(N): return [list(map(int, list(sys.stdin.readline().rstrip()))) for i in range(N)]
def S(): return sys.stdin.readline().rstrip()
def LS(): return sys.stdin.readline().split()
def LS2(N): return [sys.stdin.readline().split() for i in range(N)]
def FILL(i,h): return [i for j in range(h)]
def FILL2(i,h,w): return [FILL(i,w) for j in range(h)]
def FILL3(i,h,w,d): return [FILL2(i,w,d) for j in range(h)]
def FILL4(i,h,w,d,d2): return [FILL3(i,w,d,d2) for j in range(h)]
def sisha(num,digit): return Decimal(str(num)).quantize(Decimal(digit),rounding=ROUND_HALF_UP)
#'0.01'や'1E1'などで指定、整数に戻すならintをかます
MOD = 998244353
INF = float("inf")
sys.setrecursionlimit(10**6+10)
input = sys.stdin.readline
S = S()
S = [S[i] for i in range(len(S))]
QS= deque(S)
S = QS
Q = I()
rev = False
for i in range(Q):
    q = LS()
    if q[0] == '1':
        rev = not rev
        continue
    if (q[1] == '1') ^ rev:
        S.appendleft(q[2])
    else:
        S.append(q[2])
if rev:
    ans = ''.join(reversed(S))
else:
    ans = ''.join(S)

print(ans)

Buggy submission (verdict: Runtime Error):
import sys
import math
from decimal import Decimal, ROUND_HALF_UP, ROUND_HALF_EVEN
from collections import deque
from bisect import bisect_left
from itertools import product
def I(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LI2(N): return [list(map(int, sys.stdin.readline().split())) for i in range(N)]
def LSI(): return list(map(int, list(sys.stdin.readline().rstrip())))
def LSI2(N): return [list(map(int, list(sys.stdin.readline().rstrip()))) for i in range(N)]
def S(): return sys.stdin.readline().rstrip()
def LS(): return sys.stdin.readline().split()
def LS2(N): return [sys.stdin.readline().split() for i in range(N)]
def FILL(i,h): return [i for j in range(h)]
def FILL2(i,h,w): return [FILL(i,w) for j in range(h)]
def FILL3(i,h,w,d): return [FILL2(i,w,d) for j in range(h)]
def FILL4(i,h,w,d,d2): return [FILL3(i,w,d,d2) for j in range(h)]
def sisha(num,digit): return Decimal(str(num)).quantize(Decimal(digit),rounding=ROUND_HALF_UP)
#'0.01'や'1E1'などで指定、整数に戻すならintをかます
MOD = 998244353
INF = float("inf")
sys.setrecursionlimit(10**6+10)
input = sys.stdin.readline
S = S()
S = [S[i] for i in range(len(S))]
S = deque(S)
Q = I()
rev = False
for i in range(Q):
    q = LS()
    if q[0] == '1':
        rev = not rev
        continue
    if (q[1] == '1') ^ rev:
        S = [q[2]]+S
    else:
        S = S+q[2]
if rev:
    ans = S.reverse()
else:
    ans = S

print(ans)

Buggy submission (verdict: Runtime Error):
import sys
import math
from decimal import Decimal, ROUND_HALF_UP, ROUND_HALF_EVEN
from collections import deque
from bisect import bisect_left
from itertools import product
def I(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LI2(N): return [list(map(int, sys.stdin.readline().split())) for i in range(N)]
def LSI(): return list(map(int, list(sys.stdin.readline().rstrip())))
def LSI2(N): return [list(map(int, list(sys.stdin.readline().rstrip()))) for i in range(N)]
def S(): return sys.stdin.readline().rstrip()
def LS(): return sys.stdin.readline().split()
def LS2(N): return [sys.stdin.readline().split() for i in range(N)]
def FILL(i,h): return [i for j in range(h)]
def FILL2(i,h,w): return [FILL(i,w) for j in range(h)]
def FILL3(i,h,w,d): return [FILL2(i,w,d) for j in range(h)]
def FILL4(i,h,w,d,d2): return [FILL3(i,w,d,d2) for j in range(h)]
def sisha(num,digit): return Decimal(str(num)).quantize(Decimal(digit),rounding=ROUND_HALF_UP)
#'0.01'や'1E1'などで指定、整数に戻すならintをかます
MOD = 998244353
INF = float("inf")
sys.setrecursionlimit(10**6+10)
input = sys.stdin.readline
S = S()
S = [S[i] for i in range(len(S))]
S = deque(S)
Q = I()
rev = False
for i in range(Q):
    q = LS()
    if q[0] == '1':
        rev = not rev
        continue
    if (q[1] == '1') ^ rev:
        S = [q[2]]+S
    else:
        S = S+q[2]
if rev:
    ans = S.reverse()
else:
    ans = S

print(ans)