Buggy python submission (verdict: Time Limit Exceeded):
a, b= map(int, input().split())
pair = []
max_len = len(str(bin(b).split("b")[1]))
if a % 2 ==0:
    start = a
    remain_before = 0
else:
    start = a+1
    remain_before = a

remain_after = 0
for i in range(start, b+1,2):
    if i+1 <= b:
        pair.append((i, i+1))
    else:
        remain_after = i

if len(pair) % 2 ==0:
    print(remain_before ^ 0 ^ remain_after)
else:
    print(remain_before ^ 1 ^ remain_after)

Fixed submission:
import numpy as np
a, b= map(int, input().split())
if a % 2 ==0:
    start = a
    remain_before = 0
else:
    start = a+1
    remain_before = a

if b % 2 ==0:
    end = b-1
    remain_after = b
else:
    end = b
    remain_after = 0

if ((end+1-start) /2) %2 == 0:
    num = 0
else:
    num = 1

print(remain_before ^ num ^ remain_after)

Buggy python submission (verdict: Time Limit Exceeded):
a, b= map(int, input().split())

if a == b:
    print(a)

elif b <=10:
    ans = a
    for i in range(a+1, b+1):
        ans = ans ^ i
    print(ans)

else:
    tmpa = ""
    min_len = len(bin(a).split("b")[1])
    for i in range(min_len):
        tmpa += str(0)
    final_a = str(1) + tmpa
    final_a = int(final_a,2)
    
    tmpb = "1"
    min_len = len(bin(a).split("b")[1])
    for i in range(min_len-1):
        tmpb += str(0)
    final_b = int(tmpb,2)

    ans1 = a
    for i in range(a+1, final_a):
        ans1 = ans1 ^ i
    
    ans2 = final_b
    for i in range(final_b+1,b+1):
        ans2 = ans2 ^ i

    print(ans1 ^ans2)

Fixed submission:
import numpy as np
a, b= map(int, input().split())
if a % 2 ==0:
    start = a
    remain_before = 0
else:
    start = a+1
    remain_before = a

if b % 2 ==0:
    end = b-1
    remain_after = b
else:
    end = b
    remain_after = 0

if ((end+1-start) /2) %2 == 0:
    num = 0
else:
    num = 1

print(remain_before ^ num ^ remain_after)

Buggy python submission (verdict: Time Limit Exceeded):
a, b= map(int, input().split())

ans = a
for i in range(a+1, b+1):
    ans = ans ^ i
    
print(ans)

Fixed submission:
import numpy as np
a, b= map(int, input().split())
if a % 2 ==0:
    start = a
    remain_before = 0
else:
    start = a+1
    remain_before = a

if b % 2 ==0:
    end = b-1
    remain_after = b
else:
    end = b
    remain_after = 0

if ((end+1-start) /2) %2 == 0:
    num = 0
else:
    num = 1

print(remain_before ^ num ^ remain_after)

Buggy python submission (verdict: Time Limit Exceeded):
def xor(stra, strb):
    ans = ""
    for i in range(len(stra)):
        if (stra[i] == '0' and strb[i] =='0') or (stra[i] =='1' and strb[i] =='1'):
            ans += str(0)
        else:
            ans += str(1)
    return ans

a, b= map(int, input().split())
lista = []
cri = len(str(bin(b).split("b")[1]))
for i in range(a, b+1):
    if len(str(bin(i).split("b")[1])) < cri:
        diff = cri - len(str(bin(i).split("b")[1]))
        tmp = ""
        for j in range(diff):
            tmp += str(0)
        lista.append(tmp +str(bin(i).split("b")[1]))
    else:
        lista.append(bin(i).split("b")[1])

ans = lista[0]
for i in range(1, len(lista)):
    ans = xor(ans, lista[i])
    
print(int(ans,2))

Fixed submission:
import numpy as np
a, b= map(int, input().split())
if a % 2 ==0:
    start = a
    remain_before = 0
else:
    start = a+1
    remain_before = a

if b % 2 ==0:
    end = b-1
    remain_after = b
else:
    end = b
    remain_after = 0

if ((end+1-start) /2) %2 == 0:
    num = 0
else:
    num = 1

print(remain_before ^ num ^ remain_after)