Buggy python submission (verdict: Runtime Error):
# -*- coding: utf-8 -*-
N, K = map(int, input().split())
P = list(map(int, input().split()))
C = list(map(int, input().split()))
k_max = 5100
score = [-10**18-1] * N

for i in range(N):
  score_i = [-10**18-1] * k_max # iからスタートしてK回操作する場合の累積和
  score_i[0] = C[P[i]-1]
  index = P[i]-1
  for k in range(1, K):
    if index == i:
      # 既に進んだことがあるマスの場合
      
      loop_score = score_i[k-1] # 1ループで増えるスコア
      if loop_score > 0:
        loop_num = k # ループする要素数はk(indexが0 ~ k-1)
        
        tmp_score = [-10**18-1] * k_max
        tmp_score[0] = (K//k -1) * loop_score
#        print("loop_score", loop_score)
#        print("tmp_score", tmp_score)
        tmp_index = index
#        print("loop_num + K%k + 1", loop_num + K%k + 1)
        for j in range (1, loop_num + K%k + 1):
          tmp_score[j] = tmp_score[j-1] + C[P[tmp_index]-1]
          tmp_index = P[tmp_index]-1
#        print("max(tmp_score)", max(tmp_score))
        score_i[k] = max(tmp_score)
      break
    score_i[k] = score_i[k-1] + C[P[index]-1]
    index = P[index]-1
  score[i] = max(score_i)
print(max(score))

Fixed submission:
# -*- coding: utf-8 -*-
N, K = map(int, input().split())
P = list(map(int, input().split()))
C = list(map(int, input().split()))
k_max = 10100
score = [-10**18-1] * N

for i in range(N):
  score_i = [-10**18-1] * k_max # iからスタートしてK回操作する場合の累積和
  score_i[0] = C[P[i]-1]
  index = P[i]-1
  for k in range(1, K):
    if index == i:
      # 既に進んだことがあるマスの場合
      
      loop_score = score_i[k-1] # 1ループで増えるスコア
      if loop_score > 0:
        loop_num = k # ループする要素数はk(indexが0 ~ k-1)
        
        tmp_score = [-10**18-1] * k_max
        tmp_score[0] = (K//k -1) * loop_score
#        print("loop_score", loop_score)
#        print("tmp_score", tmp_score)
        tmp_index = index
#        print("loop_num + K%k + 1", loop_num + K%k + 1)
        for j in range (1, loop_num + K%k + 1):
          tmp_score[j] = tmp_score[j-1] + C[P[tmp_index]-1]
          tmp_index = P[tmp_index]-1
#        print("max(tmp_score)", max(tmp_score))
        score_i[k] = max(tmp_score)
      break
    score_i[k] = score_i[k-1] + C[P[index]-1]
    index = P[index]-1
  score[i] = max(score_i)
print(max(score))

Buggy python submission (verdict: Runtime Error):
# -*- coding: utf-8 -*-
N, K = map(int, input().split())
P = list(map(int, input().split()))
C = list(map(int, input().split()))
k_max = 5100
score = [0] * N

for i in range(N):
  score_i = [-10**18-1] * k_max # iからスタートしてK回操作する場合の累積和
  score_i[0] = C[P[i]-1]
  index = P[i]-1
  for k in range(1, K):
    if index == i:
      # 既に進んだことがあるマスの場合
      
      # ループ終了インデックスからループ開始インデックスの累積和の差を確認
      loop_score = score_i[k-1] # 1ループで増えるスコア
      if loop_score > 0:
        loop_num = k # ループする要素数はk(indexが0 ~ k-1)
        
        tmp_score = [-10**18-1] * k_max
        tmp_score[0] = (K//k -1) * loop_score
#        print("loop_score", loop_score)
#        print("tmp_score", tmp_score)
        tmp_index = index
        for j in range (1, loop_num + K%k+1):
          tmp_score[j] = tmp_score[j-1] + C[P[tmp_index]-1]
          tmp_index = P[tmp_index]-1
#        print("max(tmp_score)", max(tmp_score))
        score_i[k] = max(tmp_score)
      else:
        score[i] = max(score_i)
      break
    score_i[k] = score_i[k-1] + C[P[index]-1]
    index = P[index]-1
  score[i] = max(score_i)
print(max(score))

Fixed submission:
# -*- coding: utf-8 -*-
N, K = map(int, input().split())
P = list(map(int, input().split()))
C = list(map(int, input().split()))
k_max = 10100
score = [-10**18-1] * N

for i in range(N):
  score_i = [-10**18-1] * k_max # iからスタートしてK回操作する場合の累積和
  score_i[0] = C[P[i]-1]
  index = P[i]-1
  for k in range(1, K):
    if index == i:
      # 既に進んだことがあるマスの場合
      
      loop_score = score_i[k-1] # 1ループで増えるスコア
      if loop_score > 0:
        loop_num = k # ループする要素数はk(indexが0 ~ k-1)
        
        tmp_score = [-10**18-1] * k_max
        tmp_score[0] = (K//k -1) * loop_score
#        print("loop_score", loop_score)
#        print("tmp_score", tmp_score)
        tmp_index = index
#        print("loop_num + K%k + 1", loop_num + K%k + 1)
        for j in range (1, loop_num + K%k + 1):
          tmp_score[j] = tmp_score[j-1] + C[P[tmp_index]-1]
          tmp_index = P[tmp_index]-1
#        print("max(tmp_score)", max(tmp_score))
        score_i[k] = max(tmp_score)
      break
    score_i[k] = score_i[k-1] + C[P[index]-1]
    index = P[index]-1
  score[i] = max(score_i)
print(max(score))

Buggy python submission (verdict: Runtime Error):
# -*- coding: utf-8 -*-
N, K = map(int, input().split())
P = list(map(int, input().split()))
C = list(map(int, input().split()))
k_max = 5001
score = [0] * N

for i in range(N):
  score_i = [-10**18-1] * k_max # iからスタートしてK回操作する場合の累積和
  score_i[0] = C[P[i]-1]
  index = P[i]-1
  for k in range(1, K):
    if index == i:
      # 既に進んだことがあるマスの場合
      
      # ループ終了インデックスからループ開始インデックスの累積和の差を確認
      loop_score = score_i[k-1] # 1ループで増えるスコア
      if loop_score > 0:
        loop_num = k # ループする要素数はk(indexが0 ~ k-1)
        
        tmp_score = [0] * k_max
        tmp_score[0] = (K//k -1) * loop_score
        tmp_index = index
        for j in range (1, loop_num + K%k):
          tmp_score[j] = tmp_score[j-1] + C[P[tmp_index]-1]
          tmp_index = P[tmp_index]-1
        score[i] = max(tmp_score)
      else:
        score[i] = max(score_i)
      break
    else:
      if k == K-1:
        score_i[k] = score_i[k-1] + C[P[index]-1]
        score[i] = max(score_i)
        break   
    score_i[k] = score_i[k-1] + C[P[index]-1]
    index = P[index]-1
print(max(score))

Fixed submission:
# -*- coding: utf-8 -*-
N, K = map(int, input().split())
P = list(map(int, input().split()))
C = list(map(int, input().split()))
k_max = 10100
score = [-10**18-1] * N

for i in range(N):
  score_i = [-10**18-1] * k_max # iからスタートしてK回操作する場合の累積和
  score_i[0] = C[P[i]-1]
  index = P[i]-1
  for k in range(1, K):
    if index == i:
      # 既に進んだことがあるマスの場合
      
      loop_score = score_i[k-1] # 1ループで増えるスコア
      if loop_score > 0:
        loop_num = k # ループする要素数はk(indexが0 ~ k-1)
        
        tmp_score = [-10**18-1] * k_max
        tmp_score[0] = (K//k -1) * loop_score
#        print("loop_score", loop_score)
#        print("tmp_score", tmp_score)
        tmp_index = index
#        print("loop_num + K%k + 1", loop_num + K%k + 1)
        for j in range (1, loop_num + K%k + 1):
          tmp_score[j] = tmp_score[j-1] + C[P[tmp_index]-1]
          tmp_index = P[tmp_index]-1
#        print("max(tmp_score)", max(tmp_score))
        score_i[k] = max(tmp_score)
      break
    score_i[k] = score_i[k-1] + C[P[index]-1]
    index = P[index]-1
  score[i] = max(score_i)
print(max(score))

Buggy python submission (verdict: Runtime Error):
# -*- coding: utf-8 -*-
N, K = map(int, input().split())
P = list(map(int, input().split()))
C = list(map(int, input().split()))
k_max = 5001
score = [0] * N

for i in range(N):
  score_i = [-10**18-1] * k_max # iからスタートしてK回操作する場合の累積和
  score_i[0] = C[P[i]-1]
  index = P[i]-1
  for k in range(1, K):
    if index == i:
      # 既に進んだことがあるマスの場合
      
      # ループ終了インデックスからループ開始インデックスの累積和の差を確認
      loop_score = score_i[k-1] # 1ループで増えるスコア
      if loop_score > 0:
        loop_num = k # ループする要素数はk(indexが0 ~ k-1)
        
        tmp_score = [0] * k_max
        tmp_score[0] = (K//k -1) * loop_score
        tmp_index = index
        for j in range (1, loop_num + K%k + 1):
          tmp_score[j] = tmp_score[j-1] + C[P[tmp_index]-1]
          tmp_index = P[tmp_index]-1
        score[i] = max(tmp_score)
      else:
        score[i] = max(score_i)
      break
    else:
      if k == K-1:
        score_i[k] = score_i[k-1] + C[P[index]-1]
        score[i] = max(score_i)
        break   
    score_i[k] = score_i[k-1] + C[P[index]-1]
    index = P[index]-1
print(max(score))

Fixed submission:
# -*- coding: utf-8 -*-
N, K = map(int, input().split())
P = list(map(int, input().split()))
C = list(map(int, input().split()))
k_max = 10100
score = [-10**18-1] * N

for i in range(N):
  score_i = [-10**18-1] * k_max # iからスタートしてK回操作する場合の累積和
  score_i[0] = C[P[i]-1]
  index = P[i]-1
  for k in range(1, K):
    if index == i:
      # 既に進んだことがあるマスの場合
      
      loop_score = score_i[k-1] # 1ループで増えるスコア
      if loop_score > 0:
        loop_num = k # ループする要素数はk(indexが0 ~ k-1)
        
        tmp_score = [-10**18-1] * k_max
        tmp_score[0] = (K//k -1) * loop_score
#        print("loop_score", loop_score)
#        print("tmp_score", tmp_score)
        tmp_index = index
#        print("loop_num + K%k + 1", loop_num + K%k + 1)
        for j in range (1, loop_num + K%k + 1):
          tmp_score[j] = tmp_score[j-1] + C[P[tmp_index]-1]
          tmp_index = P[tmp_index]-1
#        print("max(tmp_score)", max(tmp_score))
        score_i[k] = max(tmp_score)
      break
    score_i[k] = score_i[k-1] + C[P[index]-1]
    index = P[index]-1
  score[i] = max(score_i)
print(max(score))

Buggy python submission (verdict: Runtime Error):
# -*- coding: utf-8 -*-
N, K = map(int, input().split())
P = list(map(int, input().split()))
C = list(map(int, input().split()))
k_max = 5001
score = [0] * N

for i in range(N):
  exist_i = [(False, -1)] * k_max # (exist, j)
  exist_i[i] = (True, 0)
  score_i = [0] * K # iからスタートしてK回操作する場合の累積和
  score_i[0] = C[P[i]-1]
  index = P[i]-1
  for j in range(1, K):
    if exist_i[index][0] == True:
      # 既に進んだことがあるマスの場合
      
      # ループ終了インデックスからループ開始インデックスの累積和の差を確認
      loop_score = 0
      if exist_i[index][1] >= 1:
        loop_score = score_i[j-1] - score_i[exist_i[index][1] - 1] # 1ループで増えるスコア
      else:
        loop_score = score_i[j-1]
#      print("i, j, score_i", i, j, score_i)
#      print("i, j, loop_score", i, j, loop_score)
      if loop_score > 0:
        loop_num = j - exist_i[index][1] # ループする要素数
        num = K-j # 残りの操作数
        tmp_score = score_i[j-1] + num // loop_num * loop_score # ループ前までの累積和
#        print("i, j, tmp_score", i, j, tmp_score)
        tmp_array = [0] * (num % loop_num + 1)
        tmp_array[0] = tmp_score
        for l in range(1, num % loop_num + 1):
          tmp_array[l] = tmp_array[l-1] + C[P[index]-1]
          index = P[index]-1
#        print("i, j, tmp_array", i, j, tmp_array)
        score[i] = max(tmp_array)
      else:
#        print("i, j, score_i", i, j, score_i)
        score[i] = max(score_i)
#      print("i, j, score_i", i, j, score_i)
      break
    else:
      if j == K-1:
        score_i[j] = score_i[j-1] + C[P[index]-1]
        score[i] = max(score_i)
#        print("i, j, score_i", i, j, score_i)
        break   
    score_i[j] = score_i[j-1] + C[P[index]-1]
#    print("i, j, score_i", i, j, score_i)
#    print("i, j, score", i, j, score)
    exist_i[index] = (True, j)
    index = P[index]-1
print(max(score))

Fixed submission:
# -*- coding: utf-8 -*-
N, K = map(int, input().split())
P = list(map(int, input().split()))
C = list(map(int, input().split()))
k_max = 10100
score = [-10**18-1] * N

for i in range(N):
  score_i = [-10**18-1] * k_max # iからスタートしてK回操作する場合の累積和
  score_i[0] = C[P[i]-1]
  index = P[i]-1
  for k in range(1, K):
    if index == i:
      # 既に進んだことがあるマスの場合
      
      loop_score = score_i[k-1] # 1ループで増えるスコア
      if loop_score > 0:
        loop_num = k # ループする要素数はk(indexが0 ~ k-1)
        
        tmp_score = [-10**18-1] * k_max
        tmp_score[0] = (K//k -1) * loop_score
#        print("loop_score", loop_score)
#        print("tmp_score", tmp_score)
        tmp_index = index
#        print("loop_num + K%k + 1", loop_num + K%k + 1)
        for j in range (1, loop_num + K%k + 1):
          tmp_score[j] = tmp_score[j-1] + C[P[tmp_index]-1]
          tmp_index = P[tmp_index]-1
#        print("max(tmp_score)", max(tmp_score))
        score_i[k] = max(tmp_score)
      break
    score_i[k] = score_i[k-1] + C[P[index]-1]
    index = P[index]-1
  score[i] = max(score_i)
print(max(score))