Buggy python submission (verdict: Runtime Error):
MOD=10**9+7
n,k=map(int,input().split())
a=list(map(int,input().split()))

a.sort(reverse=True)

#前計算
fact = [1]
fact_inv = [1]
mod=10**9+7
for i in range(n+1):
    new_fact = fact[-1]*(i+1)%mod
    fact.append(new_fact)
    fact_inv.append(pow(new_fact,mod-2,mod))

def mod_comb_k(n,k,mod):
    return fact[n] * fact_inv[k] % mod * fact_inv[n-k] %mod
#前計算終わり

lc=len(c)
sum=0
for i in range(lc):
  sum+=c[i]*(a[i]-a[-i-1])%MOD
  
print(sum%MOD)


Fixed submission:
MOD=10**9+7
n,k=map(int,input().split())
a=list(map(int,input().split()))

a.sort(reverse=True)


fact = [1]
fact_inv = [1]
mod=10**9+7
for i in range(10**5+1):
    new_fact = fact[-1]*(i+1)%mod
    fact.append(new_fact)
    fact_inv.append(pow(new_fact,mod-2,mod))


def mod_comb_k(n,k,mod):
    return fact[n] * fact_inv[k] % mod * fact_inv[n-k] %mod

  
c=[]
for i in range(1,n-k+1+1):
  c.append(mod_comb_k(n-i,k-1,MOD))
lc=len(c)
#print(c,a)
sum=0
for i in range(lc):
  sum+=c[i]*(a[i]-a[-i-1])%MOD
  
print(sum%MOD)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
sys.setrecursionlimit(10**5)

MOD=10**9+7
n,k=map(int,input().split())
a=list(map(int,input().split()))

a.sort(reverse=True)


from scipy.misc import comb


def mod_combination(n, k, mod):
    # nCk (mod m)
    def mod_permutation(n, k, mod):
        if n<=k:
            return 1
        else:
            return (n * mod_permutation(n-1,k,mod))%mod

    def mod_inv_permutation(k, mod):
        k, mod = int(k), int(mod)
        if k<=1:
            return 1
        else:
            return (pow(k,mod-2,mod) * mod_inv_permutation(k-1, mod))%mod

    return (mod_permutation(n,n-k,mod) * mod_inv_permutation(k, mod))%mod
  
  
c=[]
for i in range(1,n+1):
  c.append(mod_combination(n-i,k-1,MOD))
lc=len(c)
#print(c,a)
sum=0
for i in range(lc):
  sum+=c[i]*(a[i]-a[-i-1])%MOD
  
print(sum%MOD)


Fixed submission:
MOD=10**9+7
n,k=map(int,input().split())
a=list(map(int,input().split()))

a.sort(reverse=True)


fact = [1]
fact_inv = [1]
mod=10**9+7
for i in range(10**5+1):
    new_fact = fact[-1]*(i+1)%mod
    fact.append(new_fact)
    fact_inv.append(pow(new_fact,mod-2,mod))


def mod_comb_k(n,k,mod):
    return fact[n] * fact_inv[k] % mod * fact_inv[n-k] %mod

  
c=[]
for i in range(1,n-k+1+1):
  c.append(mod_comb_k(n-i,k-1,MOD))
lc=len(c)
#print(c,a)
sum=0
for i in range(lc):
  sum+=c[i]*(a[i]-a[-i-1])%MOD
  
print(sum%MOD)

Buggy python submission (verdict: Runtime Error):
MOD=10**9+7
n,k=map(int,input().split())
a=list(map(int,input().split()))

a.sort(reverse=True)


from scipy.misc import comb


def mod_combination(n, k, mod):
    # nCk (mod m)
    def mod_permutation(n, k, mod):
        if n<=k:
            return 1
        else:
            return (n * mod_permutation(n-1,k,mod))%mod

    def mod_inv_permutation(k, mod):
        k, mod = int(k), int(mod)
        if k<=1:
            return 1
        else:
            return (pow(k,mod-2,mod) * mod_inv_permutation(k-1, mod))%mod

    return (mod_permutation(n,n-k,mod) * mod_inv_permutation(k, mod))%mod
  
  
c=[]
for i in range(1,n+1):
  c.append(mod_combination(n-i,k-1,MOD))
lc=len(c)
#print(c,a)
sum=0
for i in range(lc):
  sum+=c[i]*(a[i]-a[-i-1])%MOD
  
print(sum%MOD)


Fixed submission:
MOD=10**9+7
n,k=map(int,input().split())
a=list(map(int,input().split()))

a.sort(reverse=True)


fact = [1]
fact_inv = [1]
mod=10**9+7
for i in range(10**5+1):
    new_fact = fact[-1]*(i+1)%mod
    fact.append(new_fact)
    fact_inv.append(pow(new_fact,mod-2,mod))


def mod_comb_k(n,k,mod):
    return fact[n] * fact_inv[k] % mod * fact_inv[n-k] %mod

  
c=[]
for i in range(1,n-k+1+1):
  c.append(mod_comb_k(n-i,k-1,MOD))
lc=len(c)
#print(c,a)
sum=0
for i in range(lc):
  sum+=c[i]*(a[i]-a[-i-1])%MOD
  
print(sum%MOD)

Buggy python submission (verdict: Runtime Error):
MOD=10**9+7
n,k=map(int,input().split())
a=list(map(int,input().split()))

a.sort(reverse=True)

def mod_combination(n, k, mod):
    # nCk (mod m)
    def mod_permutation(n, k, mod):
        if n<=k:
            return 1
        else:
            return (n * mod_permutation(n-1,k,mod))%mod

    def mod_inv_permutation(k, mod):
        k, mod = int(k), int(mod)
        if k<=1:
            return 1
        else:
            return (pow(k,mod-2,mod) * mod_inv_permutation(k-1, mod))%mod

    return (mod_permutation(n,n-k,mod) * mod_inv_permutation(k, mod))%mod
  
  
c=[]
for i in range(1,k):
  c.append(mod_combination(n-i,k-1,MOD))
lc=len(c)
sum=0
for i in range(lc):
  sum+=c[i]*(a[i]-a[-i-1])%MOD
  
print(sum%MOD)


Fixed submission:
MOD=10**9+7
n,k=map(int,input().split())
a=list(map(int,input().split()))

a.sort(reverse=True)


fact = [1]
fact_inv = [1]
mod=10**9+7
for i in range(10**5+1):
    new_fact = fact[-1]*(i+1)%mod
    fact.append(new_fact)
    fact_inv.append(pow(new_fact,mod-2,mod))


def mod_comb_k(n,k,mod):
    return fact[n] * fact_inv[k] % mod * fact_inv[n-k] %mod

  
c=[]
for i in range(1,n-k+1+1):
  c.append(mod_comb_k(n-i,k-1,MOD))
lc=len(c)
#print(c,a)
sum=0
for i in range(lc):
  sum+=c[i]*(a[i]-a[-i-1])%MOD
  
print(sum%MOD)

Buggy python submission (verdict: Runtime Error):
MOD=10**9+7
n,k=map(int,input().split())
a=list(map(int,input().split()))

a.sort(reverse=True)

def mod_combination(n, k, mod):
    # nCk (mod m)
    def mod_permutation(n, k, mod):
        if n<=k:
            return 1
        else:
            return (n * mod_permutation(n-1,k,mod))%mod

    def mod_inv_permutation(k, mod):
        k, mod = int(k), int(mod)
        if k<=1:
            return 1
        else:
            return (pow(k,mod-2,mod) * mod_inv_permutation(k-1, mod))%mod

    return (mod_permutation(n,n-k,mod) * mod_inv_permutation(k, mod))%mod
  
  
c=[]
for i in range(1,k):
  c.append(mod_combination(n-i,k-1,MOD))
lc=len(c)
sum=0
for i in range(lc):
  sum+=c[i]*(a[i]-a[-i-1])%MOD
  
print(sum%MOD)


Fixed submission:
MOD=10**9+7
n,k=map(int,input().split())
a=list(map(int,input().split()))

a.sort(reverse=True)


fact = [1]
fact_inv = [1]
mod=10**9+7
for i in range(10**5+1):
    new_fact = fact[-1]*(i+1)%mod
    fact.append(new_fact)
    fact_inv.append(pow(new_fact,mod-2,mod))


def mod_comb_k(n,k,mod):
    return fact[n] * fact_inv[k] % mod * fact_inv[n-k] %mod

  
c=[]
for i in range(1,n-k+1+1):
  c.append(mod_comb_k(n-i,k-1,MOD))
lc=len(c)
#print(c,a)
sum=0
for i in range(lc):
  sum+=c[i]*(a[i]-a[-i-1])%MOD
  
print(sum%MOD)

Buggy python submission (verdict: Runtime Error):
MOD=10**9+7
n,k=map(int,input().split())
a=list(map(int,input().split()))

a.sort(reverse=True)


from scipy.misc import comb
c=[]
for i in range(1,k):
  c.append(comb(n-i,k-1,exact=True)%MOD)
lc=len(c)
sum=0
for i in range(lc):
  sum+=c[i]*(a[i]-a[-i-1])%MOD
  
print(sum%MOD)


Fixed submission:
MOD=10**9+7
n,k=map(int,input().split())
a=list(map(int,input().split()))

a.sort(reverse=True)


fact = [1]
fact_inv = [1]
mod=10**9+7
for i in range(10**5+1):
    new_fact = fact[-1]*(i+1)%mod
    fact.append(new_fact)
    fact_inv.append(pow(new_fact,mod-2,mod))


def mod_comb_k(n,k,mod):
    return fact[n] * fact_inv[k] % mod * fact_inv[n-k] %mod

  
c=[]
for i in range(1,n-k+1+1):
  c.append(mod_comb_k(n-i,k-1,MOD))
lc=len(c)
#print(c,a)
sum=0
for i in range(lc):
  sum+=c[i]*(a[i]-a[-i-1])%MOD
  
print(sum%MOD)

Buggy python submission (verdict: Time Limit Exceeded):
MOD=10**9+7
n,k=map(int,input().split())
a=list(map(int,input().split()))

import itertools

p = itertools.combinations(a, k)

su=0
for i in p:
  su+=(max(i)-min(i))%MOD

print(su%MOD)

Fixed submission:
MOD=10**9+7
n,k=map(int,input().split())
a=list(map(int,input().split()))

a.sort(reverse=True)


fact = [1]
fact_inv = [1]
mod=10**9+7
for i in range(10**5+1):
    new_fact = fact[-1]*(i+1)%mod
    fact.append(new_fact)
    fact_inv.append(pow(new_fact,mod-2,mod))


def mod_comb_k(n,k,mod):
    return fact[n] * fact_inv[k] % mod * fact_inv[n-k] %mod

  
c=[]
for i in range(1,n-k+1+1):
  c.append(mod_comb_k(n-i,k-1,MOD))
lc=len(c)
#print(c,a)
sum=0
for i in range(lc):
  sum+=c[i]*(a[i]-a[-i-1])%MOD
  
print(sum%MOD)

Buggy python submission (verdict: Time Limit Exceeded):
MOD=10**9+7
n,k=map(int,input().split())
a=list(map(int,input().split()))

import itertools

p = itertools.combinations(a, k)

su=0
for i in p:
  su+=(max(i)-min(i))%MOD

print(su%MOD)

Fixed submission:
MOD=10**9+7
n,k=map(int,input().split())
a=list(map(int,input().split()))

a.sort(reverse=True)


fact = [1]
fact_inv = [1]
mod=10**9+7
for i in range(10**5+1):
    new_fact = fact[-1]*(i+1)%mod
    fact.append(new_fact)
    fact_inv.append(pow(new_fact,mod-2,mod))


def mod_comb_k(n,k,mod):
    return fact[n] * fact_inv[k] % mod * fact_inv[n-k] %mod

  
c=[]
for i in range(1,n-k+1+1):
  c.append(mod_comb_k(n-i,k-1,MOD))
lc=len(c)
#print(c,a)
sum=0
for i in range(lc):
  sum+=c[i]*(a[i]-a[-i-1])%MOD
  
print(sum%MOD)