Buggy python submission (verdict: Runtime Error):
def cmb(n, r, mod):
    if (r < 0 or r > n):
        return 0
    r=min(r,n-r)

    return g1[n] * g2[r] * g2[n - r] % mod


mod = 10 ** 9 + 7  # 出力の制限
N = 10 ** 4
g1 = [1, 1]  # 元テーブル
g2 = [1, 1]  # 逆元テーブル
inverse = [0, 1]  # 逆元テーブル計算用テーブル

for i in range(2, N + 1):
    g1.append((g1[-1] * i) % mod)
    inverse.append((-inverse[mod % i] * (mod // i)) % mod)
    g2.append((g2[-1] * inverse[-1]) % mod)

n, k = map(int, input().split())
a = list(map(int, input().split()))
a.sort()
mod =10**9+7
mi = 0
ma = 0
for i in range(n - k + 1):
    x = cmb(n - i - 1, k - 1, mod)
    mi += a[i] * x
    ma += a[n - 1 - i] * x
    mi %= mod
    ma %= mod

ans = ma - mi

print(ans % mod)

Fixed submission:
def cmb(n, r, mod):
    if (r < 0 or r > n):
        return 0
    r=min(r,n-r)

    return g1[n] * g2[r] * g2[n - r] % mod


mod = 10 ** 9 + 7  # 出力の制限
N = 10 ** 5
g1 = [1, 1]  # 元テーブル
g2 = [1, 1]  # 逆元テーブル
inverse = [0, 1]  # 逆元テーブル計算用テーブル

for i in range(2, N + 1):
    g1.append((g1[-1] * i) % mod)
    inverse.append((-inverse[mod % i] * (mod // i)) % mod)
    g2.append((g2[-1] * inverse[-1]) % mod)

n, k = map(int, input().split())
a = list(map(int, input().split()))
a.sort()
mod =10**9+7
mi = 0
ma = 0
for i in range(n - k + 1):
    x = cmb(n - i - 1, k - 1, mod)
    mi += a[i] * x
    ma += a[n - 1 - i] * x
    mi %= mod
    ma %= mod

ans = ma - mi

print(ans % mod)

Buggy python submission (verdict: Time Limit Exceeded):
def cmb(n, r):
    if n - r < r: r = n - r
    if r == 0: return 1
    if r == 1: return n

    numerator = [n - r + k + 1 for k in range(r)]
    denominator = [k + 1 for k in range(r)]

    for p in range(2,r+1):
        pivot = denominator[p - 1]
        if pivot > 1:
            offset = (n - r) % p
            for k in range(p-1,r,p):
                numerator[k - offset] /= pivot
                denominator[k] /= pivot

    result = 1
    for k in range(r):
        if numerator[k] > 1:
            result *= int(numerator[k])%mod

    return result





n, k = map(int, input().split())
a=list(map(int, input().split()))
a.sort()
mod=10**9+7
min=0
max=0
for i in range(n-k+1):
    x=cmb(n-i-1,k-1)
    min+=a[i]*x
    max+=a[n-1-i]*x
    min%=mod
    max%=mod

ans=max-min


print(ans%mod)

Fixed submission:
def cmb(n, r, mod):
    if (r < 0 or r > n):
        return 0
    r=min(r,n-r)

    return g1[n] * g2[r] * g2[n - r] % mod


mod = 10 ** 9 + 7  # 出力の制限
N = 10 ** 5
g1 = [1, 1]  # 元テーブル
g2 = [1, 1]  # 逆元テーブル
inverse = [0, 1]  # 逆元テーブル計算用テーブル

for i in range(2, N + 1):
    g1.append((g1[-1] * i) % mod)
    inverse.append((-inverse[mod % i] * (mod // i)) % mod)
    g2.append((g2[-1] * inverse[-1]) % mod)

n, k = map(int, input().split())
a = list(map(int, input().split()))
a.sort()
mod =10**9+7
mi = 0
ma = 0
for i in range(n - k + 1):
    x = cmb(n - i - 1, k - 1, mod)
    mi += a[i] * x
    ma += a[n - 1 - i] * x
    mi %= mod
    ma %= mod

ans = ma - mi

print(ans % mod)

Buggy python submission (verdict: Runtime Error):
def cmb(n, r, mod):

    if ( r<0 or r>n ):
        return 0


    return g1[n] * g2[r] * g2[n-r] % mod

mod = 10**9+7 #出力の制限
N = 10**4
g1 = [1, 1] # 元テーブル
g2 = [1, 1] #逆元テーブル
inverse = [0, 1] #逆元テーブル計算用テーブル

for i in range( 2, N + 1 ):
    g1.append( ( g1[-1] * i ) % mod )
    inverse.append( ( -inverse[mod % i] * (mod//i) ) % mod )
    g2.append( (g2[-1] * inverse[-1]) % mod )








n, k = map(int, input().split())
a=list(map(int, input().split()))
a.sort()
mod=10**9+7
min=0
max=0
for i in range(n-k+1):
    x=cmb(n-i-1,k-1,mod)
    min+=a[i]*x
    max+=a[n-1-i]*x
    min%=mod
    max%=mod

ans=max-min


print(ans%mod)

Fixed submission:
def cmb(n, r, mod):
    if (r < 0 or r > n):
        return 0
    r=min(r,n-r)

    return g1[n] * g2[r] * g2[n - r] % mod


mod = 10 ** 9 + 7  # 出力の制限
N = 10 ** 5
g1 = [1, 1]  # 元テーブル
g2 = [1, 1]  # 逆元テーブル
inverse = [0, 1]  # 逆元テーブル計算用テーブル

for i in range(2, N + 1):
    g1.append((g1[-1] * i) % mod)
    inverse.append((-inverse[mod % i] * (mod // i)) % mod)
    g2.append((g2[-1] * inverse[-1]) % mod)

n, k = map(int, input().split())
a = list(map(int, input().split()))
a.sort()
mod =10**9+7
mi = 0
ma = 0
for i in range(n - k + 1):
    x = cmb(n - i - 1, k - 1, mod)
    mi += a[i] * x
    ma += a[n - 1 - i] * x
    mi %= mod
    ma %= mod

ans = ma - mi

print(ans % mod)

Buggy python submission (verdict: Time Limit Exceeded):
import math

from operator import mul
from functools import reduce

def cmb(n, r):
    if n - r < r: r = n - r
    if r == 0: return 1
    if r == 1: return n

    numerator = [n - r + k + 1 for k in range(r)]
    denominator = [k + 1 for k in range(r)]

    for p in range(2,r+1):
        pivot = denominator[p - 1]
        if pivot > 1:
            offset = (n - r) % p
            for k in range(p-1,r,p):
                numerator[k - offset] /= pivot
                denominator[k] /= pivot

    result = 1
    for k in range(r):
        if numerator[k] > 1:
            result *= int(numerator[k])

    return result





n, k = map(int, input().split())
a=list(map(int, input().split()))
a.sort()
mod=10**9+7
min=0
max=0
for i in range(n-k+1):
    x=cmb(n-i-1,k-1)%mod
    min+=a[i]*x
    max+=a[n-1-i]*x
    min%=mod
    max%=mod

ans=max-min


print(ans%mod)

Fixed submission:
def cmb(n, r, mod):
    if (r < 0 or r > n):
        return 0
    r=min(r,n-r)

    return g1[n] * g2[r] * g2[n - r] % mod


mod = 10 ** 9 + 7  # 出力の制限
N = 10 ** 5
g1 = [1, 1]  # 元テーブル
g2 = [1, 1]  # 逆元テーブル
inverse = [0, 1]  # 逆元テーブル計算用テーブル

for i in range(2, N + 1):
    g1.append((g1[-1] * i) % mod)
    inverse.append((-inverse[mod % i] * (mod // i)) % mod)
    g2.append((g2[-1] * inverse[-1]) % mod)

n, k = map(int, input().split())
a = list(map(int, input().split()))
a.sort()
mod =10**9+7
mi = 0
ma = 0
for i in range(n - k + 1):
    x = cmb(n - i - 1, k - 1, mod)
    mi += a[i] * x
    ma += a[n - 1 - i] * x
    mi %= mod
    ma %= mod

ans = ma - mi

print(ans % mod)

Buggy python submission (verdict: Time Limit Exceeded):
import math

def combinations_count(n, r):
    return math.factorial(n) // (math.factorial(n - r) * math.factorial(r))

n, k = map(int, input().split())
a=list(map(int, input().split()))
a.sort()
mod=10**9+7
min=0
max=0
for i in range(n-k+1):

    min+=a[i]*(combinations_count(n-i-1,k-1)%mod)
    max+=a[n-1-i]*(combinations_count(n-i-1,k-1)%mod)
    min%=mod
    max%=mod

ans=max-min


print(ans%mod)

Fixed submission:
def cmb(n, r, mod):
    if (r < 0 or r > n):
        return 0
    r=min(r,n-r)

    return g1[n] * g2[r] * g2[n - r] % mod


mod = 10 ** 9 + 7  # 出力の制限
N = 10 ** 5
g1 = [1, 1]  # 元テーブル
g2 = [1, 1]  # 逆元テーブル
inverse = [0, 1]  # 逆元テーブル計算用テーブル

for i in range(2, N + 1):
    g1.append((g1[-1] * i) % mod)
    inverse.append((-inverse[mod % i] * (mod // i)) % mod)
    g2.append((g2[-1] * inverse[-1]) % mod)

n, k = map(int, input().split())
a = list(map(int, input().split()))
a.sort()
mod =10**9+7
mi = 0
ma = 0
for i in range(n - k + 1):
    x = cmb(n - i - 1, k - 1, mod)
    mi += a[i] * x
    ma += a[n - 1 - i] * x
    mi %= mod
    ma %= mod

ans = ma - mi

print(ans % mod)

Buggy python submission (verdict: Time Limit Exceeded):
import math

def combinations_count(n, r):
    return math.factorial(n) // (math.factorial(n - r) * math.factorial(r))

n, k = map(int, input().split())
a=list(map(int, input().split()))
a.sort()
mod=10**9+7
min=0
max=0
for i in range(n-k+1):

    min+=a[i]*combinations_count(n-i-1,k-1)
    max+=a[n-1-i]*combinations_count(n-i-1,k-1)
    min%=mod
    max%=mod

ans=max-min


print(ans%mod)

Fixed submission:
def cmb(n, r, mod):
    if (r < 0 or r > n):
        return 0
    r=min(r,n-r)

    return g1[n] * g2[r] * g2[n - r] % mod


mod = 10 ** 9 + 7  # 出力の制限
N = 10 ** 5
g1 = [1, 1]  # 元テーブル
g2 = [1, 1]  # 逆元テーブル
inverse = [0, 1]  # 逆元テーブル計算用テーブル

for i in range(2, N + 1):
    g1.append((g1[-1] * i) % mod)
    inverse.append((-inverse[mod % i] * (mod // i)) % mod)
    g2.append((g2[-1] * inverse[-1]) % mod)

n, k = map(int, input().split())
a = list(map(int, input().split()))
a.sort()
mod =10**9+7
mi = 0
ma = 0
for i in range(n - k + 1):
    x = cmb(n - i - 1, k - 1, mod)
    mi += a[i] * x
    ma += a[n - 1 - i] * x
    mi %= mod
    ma %= mod

ans = ma - mi

print(ans % mod)