Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.buffer.readline
N, C = map(int, input().split())
a = list(map(int, input().split()))
b = list(map(int, input().split()))
c = [[0] * (C + 1) for _ in range(N)]
mod = 10 ** 9 + 7
for i in range(N):
  c[i][0] = b[i] - a[i] + 1
for i in range(N):
  for k in range(a[i], b[i] + 1):
    t = 1
    for j in range(C):
      t *= k
      t %= mod 
      c[i][j + 1] += t
      c[i][j + 1] %= mod
dpx = [0] * (C + 1)
dpy = [0] * (C + 1)
dpx[0] = 1
for i in range(N):
  if i % 2:
    dpx = [0] * (C + 1)
  else:
    dpy = [0] * (C + 1)
  for j in range(C + 1):
    for k in range(j, C + 1):
      if i % 2:
        dpx[k] += dpy[j] * c[i][k - j]
        dpx[k] %= mod
      else:
        dpy[k] += dpx[j] * c[i][k - j]
        dpy[k] %= mod
if N % 2:
  print(dpy[-1] % mod)
else:
  print(dpx[-1] % mod)

Fixed submission:
import sys
input = sys.stdin.buffer.readline
N, C = map(int, input().split())
a = list(map(int, input().split()))
b = list(map(int, input().split()))
c = [0] * (N * (C + 1))
mod = 10 ** 9 + 7
for i in range(N):
  c[i * (C + 1)] = b[i] - a[i] + 1
for i in range(N):
  for k in range(a[i], b[i] + 1):
    t = 1
    for j in range(C):
      t *= k
      t %= mod 
      c[i * (C + 1) + j + 1] += t
      c[i * (C + 1) + j + 1] %= mod
dpx = [0] * (C + 1)
dpy = [0] * (C + 1)
dpx[0] = 1
for i in range(N):
  if i % 2:
    dpx = [0] * (C + 1)
  else:
    dpy = [0] * (C + 1)
  for j in range(C + 1):
    for k in range(j, C + 1):
      if i % 2:
        dpx[k] += dpy[j] * c[i * (C + 1) + k - j]
        dpx[k] %= mod
      else:
        dpy[k] += dpx[j] * c[i * (C + 1) + k - j]
        dpy[k] %= mod
if N % 2:
  print(dpy[-1] % mod)
else:
  print(dpx[-1] % mod)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.buffer.readline
N, C = map(int, input().split())
a = list(map(int, input().split()))
b = list(map(int, input().split()))
c = [[0] * (C + 1) for _ in range(N)]
mod = 10 ** 9 + 7
for i in range(N):
  for j in range(C + 1):
    for k in range(a[i], b[i] + 1):
      c[i][j] += pow(k, j, mod)
dpx = [0] * (C + 1)
dpy = [0] * (C + 1)
dpx[0] = 1
for i in range(N):
  if i % 2:
    dpx = [0] * (C + 1)
  else:
    dpy = [0] * (C + 1)
  for j in range(C + 1):
    for k in range(j, C + 1):
      if i % 2:
        dpx[k] += dpy[j] * c[i][k - j]
        dpx[k] %= mod
      else:
        dpy[k] += dpx[j] * c[i][k - j]
        dpy[k] %= mod
if N % 2:
  print(dpy[-1] % mod)
else:
  print(dpx[-1] % mod)

Fixed submission:
import sys
input = sys.stdin.buffer.readline
N, C = map(int, input().split())
a = list(map(int, input().split()))
b = list(map(int, input().split()))
c = [0] * (N * (C + 1))
mod = 10 ** 9 + 7
for i in range(N):
  c[i * (C + 1)] = b[i] - a[i] + 1
for i in range(N):
  for k in range(a[i], b[i] + 1):
    t = 1
    for j in range(C):
      t *= k
      t %= mod 
      c[i * (C + 1) + j + 1] += t
      c[i * (C + 1) + j + 1] %= mod
dpx = [0] * (C + 1)
dpy = [0] * (C + 1)
dpx[0] = 1
for i in range(N):
  if i % 2:
    dpx = [0] * (C + 1)
  else:
    dpy = [0] * (C + 1)
  for j in range(C + 1):
    for k in range(j, C + 1):
      if i % 2:
        dpx[k] += dpy[j] * c[i * (C + 1) + k - j]
        dpx[k] %= mod
      else:
        dpy[k] += dpx[j] * c[i * (C + 1) + k - j]
        dpy[k] %= mod
if N % 2:
  print(dpy[-1] % mod)
else:
  print(dpx[-1] % mod)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.buffer.readline
N, C = map(int, input().split())
a = list(map(int, input().split()))
b = list(map(int, input().split()))
c = [[0] * (C + 1) for _ in range(N)]
mod = 10 ** 9 + 7
for i in range(N):
  for j in range(C + 1):
    for k in range(a[i], b[i] + 1):
      c[i][j] += (k ** j) % mod
      c[i][j] %= mod
dpx = [0] * (C + 1)
dpy = [0] * (C + 1)
dpx[0] = 1
for i in range(N):
  if i % 2:
    dpx = [0] * (C + 1)
  else:
    dpy = [0] * (C + 1)
  for j in range(C + 1):
    for k in range(j, C + 1):
      if i % 2:
        dpx[k] += dpy[j] * c[i][k - j]
        dpx[k] %= mod
      else:
        dpy[k] += dpx[j] * c[i][k - j]
        dpy[k] %= mod
if N % 2:
  print(dpy[-1] % mod)
else:
  print(dpx[-1] % mod)

Fixed submission:
import sys
input = sys.stdin.buffer.readline
N, C = map(int, input().split())
a = list(map(int, input().split()))
b = list(map(int, input().split()))
c = [0] * (N * (C + 1))
mod = 10 ** 9 + 7
for i in range(N):
  c[i * (C + 1)] = b[i] - a[i] + 1
for i in range(N):
  for k in range(a[i], b[i] + 1):
    t = 1
    for j in range(C):
      t *= k
      t %= mod 
      c[i * (C + 1) + j + 1] += t
      c[i * (C + 1) + j + 1] %= mod
dpx = [0] * (C + 1)
dpy = [0] * (C + 1)
dpx[0] = 1
for i in range(N):
  if i % 2:
    dpx = [0] * (C + 1)
  else:
    dpy = [0] * (C + 1)
  for j in range(C + 1):
    for k in range(j, C + 1):
      if i % 2:
        dpx[k] += dpy[j] * c[i * (C + 1) + k - j]
        dpx[k] %= mod
      else:
        dpy[k] += dpx[j] * c[i * (C + 1) + k - j]
        dpy[k] %= mod
if N % 2:
  print(dpy[-1] % mod)
else:
  print(dpx[-1] % mod)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.buffer.readline
N, C = map(int, input().split())
a = list(map(int, input().split()))
b = list(map(int, input().split()))
c = [[0] * (C + 1) for _ in range(N)]
mod = 10 ** 9 + 7
for i in range(N):
  for j in range(C + 1):
    for k in range(a[i], b[i] + 1):
      c[i][j] += (k ** j) % mod
      c[i][j] %= mod
dp = [[0] * (C + 1) for _ in range(N + 1)]
dp[0][0] = 1
for i in range(N):
  for j in range(C + 1):
    for k in range(j, C + 1):
      dp[i + 1][k] += dp[i][j] * c[i][k - j]
      dp[i + 1][k] %= mod
print(dp[-1][-1] % mod)

Fixed submission:
import sys
input = sys.stdin.buffer.readline
N, C = map(int, input().split())
a = list(map(int, input().split()))
b = list(map(int, input().split()))
c = [0] * (N * (C + 1))
mod = 10 ** 9 + 7
for i in range(N):
  c[i * (C + 1)] = b[i] - a[i] + 1
for i in range(N):
  for k in range(a[i], b[i] + 1):
    t = 1
    for j in range(C):
      t *= k
      t %= mod 
      c[i * (C + 1) + j + 1] += t
      c[i * (C + 1) + j + 1] %= mod
dpx = [0] * (C + 1)
dpy = [0] * (C + 1)
dpx[0] = 1
for i in range(N):
  if i % 2:
    dpx = [0] * (C + 1)
  else:
    dpy = [0] * (C + 1)
  for j in range(C + 1):
    for k in range(j, C + 1):
      if i % 2:
        dpx[k] += dpy[j] * c[i * (C + 1) + k - j]
        dpx[k] %= mod
      else:
        dpy[k] += dpx[j] * c[i * (C + 1) + k - j]
        dpy[k] %= mod
if N % 2:
  print(dpy[-1] % mod)
else:
  print(dpx[-1] % mod)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.buffer.readline
N, C = map(int, input().split())
a = list(map(int, input().split()))
b = list(map(int, input().split()))
c = [[0] * (C + 1) for _ in range(N)]
mod = 10 ** 9 + 7
for i in range(N):
  for j in range(C + 1):
    for k in range(a[i], b[i] + 1):
      c[i][j] += k ** j
dp = [[0] * (C + 1) for _ in range(N + 1)]
dp[0][0] = 1
for i in range(N):
  for j in range(C + 1):
    for k in range(j, C + 1):
      dp[i + 1][k] += dp[i][j] * c[i][k - j]
      dp[i + 1][k] %= mod
print(dp[-1][-1] % mod)

Fixed submission:
import sys
input = sys.stdin.buffer.readline
N, C = map(int, input().split())
a = list(map(int, input().split()))
b = list(map(int, input().split()))
c = [0] * (N * (C + 1))
mod = 10 ** 9 + 7
for i in range(N):
  c[i * (C + 1)] = b[i] - a[i] + 1
for i in range(N):
  for k in range(a[i], b[i] + 1):
    t = 1
    for j in range(C):
      t *= k
      t %= mod 
      c[i * (C + 1) + j + 1] += t
      c[i * (C + 1) + j + 1] %= mod
dpx = [0] * (C + 1)
dpy = [0] * (C + 1)
dpx[0] = 1
for i in range(N):
  if i % 2:
    dpx = [0] * (C + 1)
  else:
    dpy = [0] * (C + 1)
  for j in range(C + 1):
    for k in range(j, C + 1):
      if i % 2:
        dpx[k] += dpy[j] * c[i * (C + 1) + k - j]
        dpx[k] %= mod
      else:
        dpy[k] += dpx[j] * c[i * (C + 1) + k - j]
        dpy[k] %= mod
if N % 2:
  print(dpy[-1] % mod)
else:
  print(dpx[-1] % mod)