Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.readline
#from itertools import accumulate
#from itertools import combinations
N,K = map(int,input().split())
P = list(map(int,input().split()))
C = list(map(int,input().split()))

#N,K = 4,4
#P = [2,3,4,1]
#C = [-9,9,1,-1]

visited = [False]*(N+1)
loops = []
for v in range(1,N+1):
    if visited[v]:
        continue
    l = [v]
    while True:
        v = l[-1]
        visited[v] = True
        nv = P[v-1]
        if visited[nv]:
            break
        l.append(nv)
    loops.append(l)

cand = []
for loop in loops:
    temp = 0
    vals = [C[i-1] for i in loop]
    l = len(vals)
    vals2 = vals+vals[:-1]
    vals3 = vals+vals+vals[:-1]
    cumsum = [0]
    for v in vals3:
        cumsum.append(cumsum[-1] + v)
    #cumsum = [0] + list(accumulate(vals2))
    gh = []
    #print(vals)
    if K <= l:
        temp = 0
        for left in range(0,2*l-K):
            for right in range(left+1,left+K+1):
                gh.append(cumsum[right] - cumsum[left])
        if gh:
            temp = max(gh)
    else:
        temp = 0
        s = sum(vals)
        q, r = divmod(K,l)
        q -= 1
        r += l
        for left in range(0,3*l-r):
            for right in range(left+1,left+r+1):
                #print(left,right)
                gh.append(cumsum[right] - cumsum[left])
        if gh:
            temp = max(gh)
        if s > 0:
            temp += q * s
    cand.append(temp)
print(max(cand))






Fixed submission:
import sys
input = sys.stdin.readline
#from itertools import accumulate
#from itertools import combinations
N,K = map(int,input().split())
P = list(map(int,input().split()))
C = list(map(int,input().split()))

#N,K = 4,4
#P = [2,3,4,1]
#C = [-9,9,1,-1]
#N = 5000
#K = 10**8
#P = [i+1 for i in range(1,5000)] + [1]
#C = [10**9] * N

visited = [False]*(N+1)
loops = []
for v in range(1,N+1):
    if visited[v]:
        continue
    l = [v]
    while True:
        v = l[-1]
        visited[v] = True
        nv = P[v-1]
        if visited[nv]:
            break
        l.append(nv)
    loops.append(l)

cand = []
for loop in loops:
    temp = 0
    vals = [C[i-1] for i in loop]
    l = len(vals)
    vals3 = vals+vals+vals[:-1]
    cumsum = [0]
    for v in vals3:
        cumsum.append(cumsum[-1] + v)
    gh = []
    #print(vals)
    if K <= l:
        temp = 0
        ma = min(vals)
        for left in range(0,2*l-K):
            for right in range(left+1,left+K+1):
                ma = max(ma,(cumsum[right] - cumsum[left]))
        temp += ma
    else:
        temp = 0
        s = sum(vals)
        q, r = divmod(K,l)
        q -= 1
        r += l
        ma = min(vals)
        for left in range(0,3*l-r):
            for right in range(left+1,left+r+1):
                ma = max(ma,(cumsum[right] - cumsum[left]))
        temp += ma
        if s > 0:
            temp += q * s
    cand.append(temp)
print(max(cand))

Buggy python submission (verdict: Runtime Error):
import sys
input = sys.stdin.readline
#from itertools import accumulate
#from itertools import combinations
N,K = map(int,input().split())
P = list(map(int,input().split()))
C = list(map(int,input().split()))

visited = [False]*(N+1)
loops = []
for v in range(1,N+1):
    if visited[v]:
        continue
    l = [v]
    while True:
        v = l[-1]
        visited[v] = True
        nv = P[v-1]
        if visited[nv]:
            break
        l.append(nv)
    loops.append(l)

cand = []
for loop in loops:
    temp = 0
    vals = [C[i-1] for i in loop]
    l = len(vals)
    vals2 = vals+vals[:-1]
    cumsum = [0]
    for v in vals2:
        cumsum.append(cumsum[-1] + v)
    #cumsum = [0] + list(accumulate(vals2))
    gh = []
    #print(vals)
    if K <= l:
        for left in range(0,2*l-K):
            for right in range(left+1,left+K+1):
                gh.append(cumsum[right] - cumsum[left])
        temp = max(gh)
    else:
        s = sum(vals)
        q, r = divmod(K,l)
        for left in range(0,2*l-r):
            for right in range(left+1,left+r+1):
                gh.append(cumsum[right] - cumsum[left])
        temp = max(gh)
        if s > 0:
            temp += q * s
    #print(temp)
    cand.append(temp)
print(max(cand))






Fixed submission:
import sys
input = sys.stdin.readline
#from itertools import accumulate
#from itertools import combinations
N,K = map(int,input().split())
P = list(map(int,input().split()))
C = list(map(int,input().split()))

#N,K = 4,4
#P = [2,3,4,1]
#C = [-9,9,1,-1]
#N = 5000
#K = 10**8
#P = [i+1 for i in range(1,5000)] + [1]
#C = [10**9] * N

visited = [False]*(N+1)
loops = []
for v in range(1,N+1):
    if visited[v]:
        continue
    l = [v]
    while True:
        v = l[-1]
        visited[v] = True
        nv = P[v-1]
        if visited[nv]:
            break
        l.append(nv)
    loops.append(l)

cand = []
for loop in loops:
    temp = 0
    vals = [C[i-1] for i in loop]
    l = len(vals)
    vals3 = vals+vals+vals[:-1]
    cumsum = [0]
    for v in vals3:
        cumsum.append(cumsum[-1] + v)
    gh = []
    #print(vals)
    if K <= l:
        temp = 0
        ma = min(vals)
        for left in range(0,2*l-K):
            for right in range(left+1,left+K+1):
                ma = max(ma,(cumsum[right] - cumsum[left]))
        temp += ma
    else:
        temp = 0
        s = sum(vals)
        q, r = divmod(K,l)
        q -= 1
        r += l
        ma = min(vals)
        for left in range(0,3*l-r):
            for right in range(left+1,left+r+1):
                ma = max(ma,(cumsum[right] - cumsum[left]))
        temp += ma
        if s > 0:
            temp += q * s
    cand.append(temp)
print(max(cand))

Buggy python submission (verdict: Runtime Error):
import sys
input = sys.stdin.readline
from itertools import accumulate
from itertools import combinations
N,K = map(int,input().split())
P = list(map(int,input().split()))
C = list(map(int,input().split()))

visited = [False]*(N+1)
loops = []
for v in range(1,N+1):
    if visited[v]:
        continue
    l = [v]
    while True:
        v = l[-1]
        visited[v] = True
        nv = P[v-1]
        if visited[nv]:
            break
        l.append(nv)
    loops.append(l)

cand = []
for loop in loops:
    temp = 0
    vals = [C[i-1] for i in loop]
    l = len(vals)
    vals2 = vals+vals[:-1]
    cumsum = [0] + list(accumulate(vals2))
    gh = []
    #print(vals)
    if K <= l:
        for right,left in combinations(range(2*l), 2):
            if left - right <= K:
                gh.append(cumsum[left] - cumsum[right])
        temp = max(gh)
        #print(vals2,cumsum,gh)
    else:
        s = sum(vals)

        q, r = divmod(K,l)
        for right,left in combinations(range(2*l), 2):
            if left - right <= r:
                gh.append(cumsum[left] - cumsum[right])
        temp = max(gh)
        if s > 0:
            temp += q * s
    #print(temp)
    cand.append(temp)
print(max(cand))






Fixed submission:
import sys
input = sys.stdin.readline
#from itertools import accumulate
#from itertools import combinations
N,K = map(int,input().split())
P = list(map(int,input().split()))
C = list(map(int,input().split()))

#N,K = 4,4
#P = [2,3,4,1]
#C = [-9,9,1,-1]
#N = 5000
#K = 10**8
#P = [i+1 for i in range(1,5000)] + [1]
#C = [10**9] * N

visited = [False]*(N+1)
loops = []
for v in range(1,N+1):
    if visited[v]:
        continue
    l = [v]
    while True:
        v = l[-1]
        visited[v] = True
        nv = P[v-1]
        if visited[nv]:
            break
        l.append(nv)
    loops.append(l)

cand = []
for loop in loops:
    temp = 0
    vals = [C[i-1] for i in loop]
    l = len(vals)
    vals3 = vals+vals+vals[:-1]
    cumsum = [0]
    for v in vals3:
        cumsum.append(cumsum[-1] + v)
    gh = []
    #print(vals)
    if K <= l:
        temp = 0
        ma = min(vals)
        for left in range(0,2*l-K):
            for right in range(left+1,left+K+1):
                ma = max(ma,(cumsum[right] - cumsum[left]))
        temp += ma
    else:
        temp = 0
        s = sum(vals)
        q, r = divmod(K,l)
        q -= 1
        r += l
        ma = min(vals)
        for left in range(0,3*l-r):
            for right in range(left+1,left+r+1):
                ma = max(ma,(cumsum[right] - cumsum[left]))
        temp += ma
        if s > 0:
            temp += q * s
    cand.append(temp)
print(max(cand))