Problem p02756 (python)

Fixed submission:
S = input()
Q = int(input())
query_list = []
for i in range(Q):
    query_list.append(input())
# print(S, Q, query_list)

M = 10 ** 6
start_position = int(M / 2)
left_position = start_position
right_position = start_position + len(S)
result = ["-"] * M
for i in range(len(S)):
    # print(i + left_position)
    result[i + left_position] = S[i]

# result = "".join(result[left_position:right_position])
# print(result)
# exit(0)
reverse_flag = False

for i in range(Q):
    # print(i + 1)
    # print(result[left_position:right_position])
    q = query_list[i]
    # print(q)
    t = int(q[0])
    if t == 1:
        reverse_flag = not reverse_flag
    else:
        t, f, c = q.split()
        f = int(f)
        c = c
        if f == 1:
            if reverse_flag:
                result[right_position] = c
                right_position += 1
            else:
                result[left_position - 1] = c
                left_position -= 1
        else:
            if reverse_flag:
                result[left_position - 1] = c
                left_position -= 1
            else:
                result[right_position] = c
                right_position += 1
    # print(t, f, c, result)
    # print("--------")
    #print(result[left_position:right_position])
# result = str(result)
# result = "".join(result)
# print(result)
# print(result[left_position:right_position])

result = "".join(result[left_position:right_position])
if reverse_flag:
    result = result[::-1]
print(result)

Buggy submission (verdict: Runtime Error):
S = input()
Q = int(input())
query_list = []
for i in range(Q):
    query_list.append(input())
# print(S, Q, query_list)

M = 10 ** 6
start_position = int(M / 2)
left_position = start_position
right_position = start_position + len(S)
result = ["-"] * M
for i in range(len(S)):
    # print(i + left_position)
    result[i + left_position] = S[i]

# result = "".join(result[left_position:right_position])
# print(result)
# exit(0)
reverse_flag = False

for i in range(Q):
    # print(i + 1)
    # print(result[left_position:right_position])
    q = query_list[i]
    # print(q)
    t = int(q[0])
    if t == 1:
        reverse_flag = not reverse_flag
    else:
        t, f, c = q.split()
        f = int(f)
        c = c
        if f == 1:
            if reverse_flag:
                result[right_position] = c
                right_position += 1
            else:
                result[left_position - 1] = c
                left_position -= 1
        else:
            if reverse_flag:
                result[left_position - 1] = c
                left_position -= 1
            else:
                result[right_position] = c
                right_position += 1
    # print(t, f, c, result)
    # print("--------")
    print(result[left_position:right_position])
# result = str(result)
# result = "".join(result)
# print(result)
# print(result[left_position:right_position])

result = "".join(result[left_position:right_position])
if reverse_flag:
    result = result[::-1]
print(result)

Buggy submission (verdict: Runtime Error):
S = input()
Q = int(input())
query_list = []
for i in range(Q):
    query_list.append(input())
# print(S, Q, query_list)

result = S
reverse_flag = False

for i in range(Q):
    # print(i + 1)
    q = query_list[i]
    # print(q)
    t = int(q[0])
    if t == 1:
        reverse_flag = not reverse_flag
    else:
        t, f, c = q.split()
        f = int(f)
        if f == 1:
            if reverse_flag:
                result = f"{result}{c}"
            else:
                #result = c + result
                result = f"{c}{result}"
        else:
            if reverse_flag:
                #result = c + result
                result = f"{c}{result}"
            else:
                #result = result + c
                result = f"{result}{c}"
    # print(t, f, c, result)
    # print("--------")
if reverse_flag:
    result = result[::-1]
print(result)