Buggy python submission (verdict: Runtime Error):
# coding: utf-8
import sys
#from operator import itemgetter
sysread = sys.stdin.buffer.readline
read = sys.stdin.buffer.read
#from heapq import heappop, heappush
#from collections import defaultdict
sys.setrecursionlimit(10**7)
#import math
#from itertools import product, accumulate, combinations, product
#import bisect
#import numpy as np
#from copy import deepcopy
#from collections import deque
#from decimal import Decimal

INF = 1 << 100


def run():
    N, K = map(int, sysread().split())
    P = list(map(int, sysread().split()))
    C = list(map(int, sysread().split()))
    P = [p-1 for p in P]

    loops = []
    checked = [0] * N
    loop = [0]
    for i in range(N):
        current = i
        while True:
            if not checked[current]:
                checked[current] = 1
                loop.append(C[current])
                current = P[current]
            else:
                if len(loop) == 1:break
                loops.append(loop)
                loop = [0]
                break
    loopSums = []
    for loop in loops:
        val = 0
        tmp = []
        for l in loop:
            val += l
            tmp.append(val)
        loopSums.append(tmp)
    #print(loops)
    #print(loopSums)
    ans = -INF
    for loop, loopSum in zip(loops, loopSums):
        for i in range(1, len(loop)):
            val = 0
            if loopSum[-1] <= 0 or len(loop)-1 > K:
                j = i
                max_val = -INF
                iter = 0
                done = False
                while iter <= K:
                    if j >= len(loop):j=0
                    if (i != j and j) or done:
                        val += loop[j]
                        max_val = max(val, max_val)
                    j += 1
                    if not j ==1:
                        iter += 1
                    if done : break
                    if i == j: done = True
                ans = max(ans, max_val)
                continue


            rest = K
            #if K <= len(loop) - i - 1:
            #    val += loopSum[i + K - 1] - loopSum[i]
            #    ans = max(ans, val)
            #    continue
            rest -= len(loop) - i - 1
            val += loopSum[-1] - loopSum[i]
            val += (rest // (len(loop)-1)) * loopSum[-1]
            rest = rest % (len(loop) - 1)
            if not rest:
                val += max(loopSum[1:rest+1])
            ans = max(ans, val)

    print(ans)

if __name__ == "__main__":
    run()

Fixed submission:
# coding: utf-8
import sys
#from operator import itemgetter
sysread = sys.stdin.buffer.readline
read = sys.stdin.buffer.read
#from heapq import heappop, heappush
#from collections import defaultdict
sys.setrecursionlimit(10**7)
#import math
#from itertools import product, accumulate, combinations, product
#import bisect
#import numpy as np
#from copy import deepcopy
#from collections import deque
#from decimal import Decimal

INF = 1 << 100


def run():
    N, K = map(int, sysread().split())
    P = list(map(int, sysread().split()))
    C = list(map(int, sysread().split()))
    P = [p-1 for p in P]

    loops = []
    checked = [0] * N
    loop = [0]
    for i in range(N):
        current = i
        while True:
            if not checked[current]:
                checked[current] = 1
                loop.append(C[current])
                current = P[current]
            else:
                if len(loop) == 1:break
                loops.append(loop)
                loop = [0]
                break
    loopSums = []
    for loop in loops:
        val = 0
        tmp = []
        for l in loop:
            val += l
            tmp.append(val)
        loopSums.append(tmp)
    #print(loops)
    #print(loopSums)
    ans = -INF
    for loop, loopSum in zip(loops, loopSums):
        for i in range(1, len(loop)):
            val = 0
            if loopSum[-1] <= 0 or len(loop)-1 > K:
                j = i
                max_val = -INF
                iter = 0
                while iter < K:
                    iter += 1
                    j += 1
                    if j == len(loop):
                        j = 1
                    val += loop[j]
                    max_val = max(max_val, val)
                    if i == j:
                        break
                #print(max_val)
                ans = max(ans, max_val)
                continue


            rest = K
            #if K <= len(loop) - i - 1:
            #    val += loopSum[i + K - 1] - loopSum[i]
            #    ans = max(ans, val)
            #    continue
            rest -= len(loop) - i - 1
            val += loopSum[-1] - loopSum[i]
            if rest // (len(loop)-1):
                val1 = val + (rest // (len(loop)-1)) * loopSum[-1]
                rest1 = rest % (len(loop) - 1)
                if rest1:
                    val1 += max(loopSum[1:rest1+1])
                val2 = val + (rest // (len(loop)-1) - 1) * loopSum[-1]
                val2 += max(loopSum[1:])
                val = max(val1, val2)
            else:
                if rest:
                    val += max(loopSum[1:rest+1])
            ans = max(ans, val)

    print(ans)

if __name__ == "__main__":
    run()

Buggy python submission (verdict: Runtime Error):
# coding: utf-8
import sys
#from operator import itemgetter
sysread = sys.stdin.buffer.readline
read = sys.stdin.buffer.read
#from heapq import heappop, heappush
#from collections import defaultdict
sys.setrecursionlimit(10**7)
#import math
#from itertools import product, accumulate, combinations, product
#import bisect
#import numpy as np
#from copy import deepcopy
#from collections import deque
#from decimal import Decimal

INF = 1 << 100


def run():
    N, K = map(int, sysread().split())
    P = list(map(int, sysread().split()))
    C = list(map(int, sysread().split()))
    P = [p-1 for p in P]

    loops = []
    checked = [0] * N
    loop = [0]
    for i in range(N):
        current = i
        while True:
            if not checked[current]:
                checked[current] = 1
                loop.append(C[current])
                current = P[current]
            else:
                if len(loop) == 1:break
                loops.append(loop)
                loop = [0]
                break
    loopSums = []
    for loop in loops:
        val = 0
        tmp = []
        for l in loop:
            val += l
            tmp.append(val)
        loopSums.append(tmp)
    #print(loops)
    #print(loopSums)
    ans = -INF
    for loop, loopSum in zip(loops, loopSums):
        for i in range(1, len(loop)):
            val = 0
            if loopSum[-1] <= 0 or len(loop)-1 > K:
                j = i
                max_val = -INF
                iter = 0
                done = False
                while iter <= K:
                    if j >= len(loop):j=0
                    if (i != j and j) or done:
                        val += loop[j]
                        max_val = max(val, max_val)
                    j += 1
                    if not j ==1:
                        iter += 1
                    if done : break
                    if i == j: done = True
                ans = max(ans, max_val)
                continue


            rest = K
            #if K <= len(loop) - i - 1:
            #    val += loopSum[i + K - 1] - loopSum[i]
            #    ans = max(ans, val)
            #    continue
            rest -= len(loop) - i - 1
            val += loopSum[-1] - loopSum[i]
            val += (rest // (len(loop)-1)) * loopSum[-1]
            rest = rest % (len(loop) - 1)
            val += max(loopSum[1:rest+1])
            ans = max(ans, val)

    print(ans)

if __name__ == "__main__":
    run()

Fixed submission:
# coding: utf-8
import sys
#from operator import itemgetter
sysread = sys.stdin.buffer.readline
read = sys.stdin.buffer.read
#from heapq import heappop, heappush
#from collections import defaultdict
sys.setrecursionlimit(10**7)
#import math
#from itertools import product, accumulate, combinations, product
#import bisect
#import numpy as np
#from copy import deepcopy
#from collections import deque
#from decimal import Decimal

INF = 1 << 100


def run():
    N, K = map(int, sysread().split())
    P = list(map(int, sysread().split()))
    C = list(map(int, sysread().split()))
    P = [p-1 for p in P]

    loops = []
    checked = [0] * N
    loop = [0]
    for i in range(N):
        current = i
        while True:
            if not checked[current]:
                checked[current] = 1
                loop.append(C[current])
                current = P[current]
            else:
                if len(loop) == 1:break
                loops.append(loop)
                loop = [0]
                break
    loopSums = []
    for loop in loops:
        val = 0
        tmp = []
        for l in loop:
            val += l
            tmp.append(val)
        loopSums.append(tmp)
    #print(loops)
    #print(loopSums)
    ans = -INF
    for loop, loopSum in zip(loops, loopSums):
        for i in range(1, len(loop)):
            val = 0
            if loopSum[-1] <= 0 or len(loop)-1 > K:
                j = i
                max_val = -INF
                iter = 0
                while iter < K:
                    iter += 1
                    j += 1
                    if j == len(loop):
                        j = 1
                    val += loop[j]
                    max_val = max(max_val, val)
                    if i == j:
                        break
                #print(max_val)
                ans = max(ans, max_val)
                continue


            rest = K
            #if K <= len(loop) - i - 1:
            #    val += loopSum[i + K - 1] - loopSum[i]
            #    ans = max(ans, val)
            #    continue
            rest -= len(loop) - i - 1
            val += loopSum[-1] - loopSum[i]
            if rest // (len(loop)-1):
                val1 = val + (rest // (len(loop)-1)) * loopSum[-1]
                rest1 = rest % (len(loop) - 1)
                if rest1:
                    val1 += max(loopSum[1:rest1+1])
                val2 = val + (rest // (len(loop)-1) - 1) * loopSum[-1]
                val2 += max(loopSum[1:])
                val = max(val1, val2)
            else:
                if rest:
                    val += max(loopSum[1:rest+1])
            ans = max(ans, val)

    print(ans)

if __name__ == "__main__":
    run()

Buggy python submission (verdict: Runtime Error):
# coding: utf-8
import sys
#from operator import itemgetter
sysread = sys.stdin.buffer.readline
read = sys.stdin.buffer.read
#from heapq import heappop, heappush
#from collections import defaultdict
sys.setrecursionlimit(10**7)
#import math
#from itertools import product, accumulate, combinations, product
#import bisect
#import numpy as np
#from copy import deepcopy
#from collections import deque
#from decimal import Decimal

INF = 1 << 63


def run():
    N, K = map(int, sysread().split())
    P = list(map(int, sysread().split()))
    C = list(map(int, sysread().split()))
    P = [p-1 for p in P]

    loops = []
    checked = [0] * N
    loop = [0]
    for i in range(N):
        current = i
        while True:
            if not checked[current]:
                checked[current] = 1
                loop.append(C[current])
                current = P[current]
            else:
                if len(loop) == 1:break
                loops.append(loop)
                loop = [0]
                break
    loopSums = []
    for loop in loops:
        val = 0
        tmp = []
        for l in loop:
            val += l
            tmp.append(val)
        loopSums.append(tmp)
    #print(loops)
    #print(loopSums)
    ans = -INF
    for loop, loopSum in zip(loops, loopSums):
        for i in range(1, len(loop)):
            val = 0
            if loopSum[-1] < 0 or K <= len(loop)-2:
                j = i
                max_val = -INF
                iter = 0
                done = False
                while iter <= K:
                    if j >= len(loop):j=0
                    if i != j and j:
                        val += loop[j]
                        max_val = max(val, max_val)
                    j += 1
                    iter += 1
                    if done : break
                    if i == j: done = True
                ans = max(ans, max_val)
                continue


            rest = K
            #if K <= len(loop) - i - 1:
            #    val += loopSum[i + K - 1] - loopSum[i]
            #    ans = max(ans, val)
            #    continue
            rest -= len(loop) - i - 1
            val += loopSum[-1] - loopSum[i]
            val += (rest // (len(loop)-1)) * loopSum[-1]
            rest = rest % (len(loop) - 1)
            val += max(loopSum[:rest])
            ans = max(ans, val)

    print(ans)

if __name__ == "__main__":
    run()

Fixed submission:
# coding: utf-8
import sys
#from operator import itemgetter
sysread = sys.stdin.buffer.readline
read = sys.stdin.buffer.read
#from heapq import heappop, heappush
#from collections import defaultdict
sys.setrecursionlimit(10**7)
#import math
#from itertools import product, accumulate, combinations, product
#import bisect
#import numpy as np
#from copy import deepcopy
#from collections import deque
#from decimal import Decimal

INF = 1 << 100


def run():
    N, K = map(int, sysread().split())
    P = list(map(int, sysread().split()))
    C = list(map(int, sysread().split()))
    P = [p-1 for p in P]

    loops = []
    checked = [0] * N
    loop = [0]
    for i in range(N):
        current = i
        while True:
            if not checked[current]:
                checked[current] = 1
                loop.append(C[current])
                current = P[current]
            else:
                if len(loop) == 1:break
                loops.append(loop)
                loop = [0]
                break
    loopSums = []
    for loop in loops:
        val = 0
        tmp = []
        for l in loop:
            val += l
            tmp.append(val)
        loopSums.append(tmp)
    #print(loops)
    #print(loopSums)
    ans = -INF
    for loop, loopSum in zip(loops, loopSums):
        for i in range(1, len(loop)):
            val = 0
            if loopSum[-1] <= 0 or len(loop)-1 > K:
                j = i
                max_val = -INF
                iter = 0
                while iter < K:
                    iter += 1
                    j += 1
                    if j == len(loop):
                        j = 1
                    val += loop[j]
                    max_val = max(max_val, val)
                    if i == j:
                        break
                #print(max_val)
                ans = max(ans, max_val)
                continue


            rest = K
            #if K <= len(loop) - i - 1:
            #    val += loopSum[i + K - 1] - loopSum[i]
            #    ans = max(ans, val)
            #    continue
            rest -= len(loop) - i - 1
            val += loopSum[-1] - loopSum[i]
            if rest // (len(loop)-1):
                val1 = val + (rest // (len(loop)-1)) * loopSum[-1]
                rest1 = rest % (len(loop) - 1)
                if rest1:
                    val1 += max(loopSum[1:rest1+1])
                val2 = val + (rest // (len(loop)-1) - 1) * loopSum[-1]
                val2 += max(loopSum[1:])
                val = max(val1, val2)
            else:
                if rest:
                    val += max(loopSum[1:rest+1])
            ans = max(ans, val)

    print(ans)

if __name__ == "__main__":
    run()