Buggy python submission (verdict: Runtime Error):
import math

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 = list(map(int,input().split()))
A = sorted(tuple(map(int,input().split())))
B = tuple(A[i+1]-A[i]  for i in range(len(A)-1))
lim = math.ceil(len(B)/2)

L = 10**9+7
ans = 0
multi = cmb(N,K,mod)
for j in range(lim):
    front = j + 1
    back = N - front
    tmp_b = 0
    tmp_f = 0
    if front >= K:
        tmp_f = cmb(front,K,mod)
    if back >= K:
        tmp_b = cmb(back,K,mod)
    if j == (len(B)-1)/2:
        ans += (multi - tmp_b - tmp_f)*(B[j]) % L
    else:
        ans += (multi - tmp_b - tmp_f)*(B[j]+B[len(B)-1-j]) % L
print(ans%L)

Fixed submission:
import math

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+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 = list(map(int,input().split()))
A = sorted(tuple(map(int,input().split())))
B = tuple(A[i+1]-A[i]  for i in range(len(A)-1))
lim = math.ceil(len(B)/2)

L = 10**9+7
ans = 0
multi = cmb(N,K,mod)
for j in range(lim):
    front = j + 1
    back = N - front
    tmp_b = 0
    tmp_f = 0
    if front >= K:
        tmp_f = cmb(front,K,mod)
    if back >= K:
        tmp_b = cmb(back,K,mod)
    if j == (len(B)-1)/2:
        ans += (multi - tmp_b - tmp_f)*(B[j]) % L
    else:
        ans += (multi - tmp_b - tmp_f)*(B[j]+B[len(B)-1-j]) % L
print(ans%L)

Buggy python submission (verdict: Runtime Error):
import math

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 = list(map(int,input().split()))
A = sorted(tuple(map(int,input().split())))
B = tuple(A[i+1]-A[i]  for i in range(len(A)-1))
lim = math.ceil(len(B)/2)

L = 10**9+7
ans = 0
multi = cmb(N,K,mod)
for j in range(lim):
    front = j + 1
    back = N - front
    tmp_b = 0
    tmp_f = 0
    if front >= K:
        tmp_f = cmb(front,K,mod)
    if back >= K:
        tmp_b = cmb(back,K,mod)
    if j == (len(B)-1)/2:
        ans += (multi - tmp_b - tmp_f)*(B[j]) % L
    else:
        ans += (multi - tmp_b - tmp_f)*(B[j]+B[len(B)-1-j]) % L
print(ans%L)

Fixed submission:
import math

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+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 = list(map(int,input().split()))
A = sorted(tuple(map(int,input().split())))
B = tuple(A[i+1]-A[i]  for i in range(len(A)-1))
lim = math.ceil(len(B)/2)

L = 10**9+7
ans = 0
multi = cmb(N,K,mod)
for j in range(lim):
    front = j + 1
    back = N - front
    tmp_b = 0
    tmp_f = 0
    if front >= K:
        tmp_f = cmb(front,K,mod)
    if back >= K:
        tmp_b = cmb(back,K,mod)
    if j == (len(B)-1)/2:
        ans += (multi - tmp_b - tmp_f)*(B[j]) % L
    else:
        ans += (multi - tmp_b - tmp_f)*(B[j]+B[len(B)-1-j]) % L
print(ans%L)

Buggy python submission (verdict: Runtime Error):
import math

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 = list(map(int,input().split()))
A = sorted(tuple(map(int,input().split())))
B = tuple(A[i+1]-A[i]  for i in range(len(A)-1))
lim = math.ceil(len(B)/2)

L = 10**9+7
ans = 0
multi = cmb(N,K,mod)
for j in range(lim):
    front = j + 1
    back = N - front
    tmp_b = 0
    tmp_f = 0
    if front >= K:
        tmp_f = cmb(front,K,mod)
    if back >= K:
        tmp_b = cmb(back,K,mod)
    if j == (len(B)-1)/2:
        ans += (multi - tmp_b - tmp_f)*(B[j]) % L
    else:
        ans += (multi - tmp_b - tmp_f)*(B[j]+B[len(B)-1-j]) % L
print(ans%L)

Fixed submission:
import math

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+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 = list(map(int,input().split()))
A = sorted(tuple(map(int,input().split())))
B = tuple(A[i+1]-A[i]  for i in range(len(A)-1))
lim = math.ceil(len(B)/2)

L = 10**9+7
ans = 0
multi = cmb(N,K,mod)
for j in range(lim):
    front = j + 1
    back = N - front
    tmp_b = 0
    tmp_f = 0
    if front >= K:
        tmp_f = cmb(front,K,mod)
    if back >= K:
        tmp_b = cmb(back,K,mod)
    if j == (len(B)-1)/2:
        ans += (multi - tmp_b - tmp_f)*(B[j]) % L
    else:
        ans += (multi - tmp_b - tmp_f)*(B[j]+B[len(B)-1-j]) % L
print(ans%L)

Buggy python submission (verdict: Runtime Error):
import math

from scipy.special import comb
# a = comb(n, r)
#a = comb(n, r, exact=True)

N,K = list(map(int,input().split()))
A = sorted(tuple(map(int,input().split())))
B = tuple(A[i+1]-A[i]  for i in range(len(A)-1))
lim = math.ceil(len(B)/2)

L = 10**9+7
ans = 0
multi = comb(N,K,exact=True)
for j in range(lim):
    front = j + 1
    back = N - front
    tmp_b = 0
    tmp_f = 0
    if front >= K:
        tmp_f = comb(front,K,exact=True) % L
    if back >= K:
        tmp_b = comb(back,K,exact=True) % L
    if j == (len(B)-1)/2:
        ans += (multi - tmp_b - tmp_f)*(B[j]) % L
    else:
        ans += (multi - tmp_b - tmp_f)*(B[j]+B[len(B)-1-j]) % L
print(ans%L)

Fixed submission:
import math

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+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 = list(map(int,input().split()))
A = sorted(tuple(map(int,input().split())))
B = tuple(A[i+1]-A[i]  for i in range(len(A)-1))
lim = math.ceil(len(B)/2)

L = 10**9+7
ans = 0
multi = cmb(N,K,mod)
for j in range(lim):
    front = j + 1
    back = N - front
    tmp_b = 0
    tmp_f = 0
    if front >= K:
        tmp_f = cmb(front,K,mod)
    if back >= K:
        tmp_b = cmb(back,K,mod)
    if j == (len(B)-1)/2:
        ans += (multi - tmp_b - tmp_f)*(B[j]) % L
    else:
        ans += (multi - tmp_b - tmp_f)*(B[j]+B[len(B)-1-j]) % L
print(ans%L)

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 = list(map(int,input().split()))
A = sorted(tuple(map(int,input().split())))
B = tuple(A[i+1]-A[i]  for i in range(len(A)-1))
lim = math.ceil(len(B)/2)

L = 10**9+7
ans = 0
multi = combinations_count(N,K)
for j in range(lim):
    front = j + 1
    back = N - front
    tmp_b = 0
    tmp_f = 0
    if front >= K:
        tmp_f = combinations_count(front,K) % L
    if back >= K:
        tmp_b = combinations_count(back,K) % L
    if j == (len(B)-1)/2:
        ans += (multi - tmp_b - tmp_f)*(B[j]) % L
    else:
        ans += (multi - tmp_b - tmp_f)*(B[j]+B[len(B)-1-j]) % L
print(ans%L)

Fixed submission:
import math

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+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 = list(map(int,input().split()))
A = sorted(tuple(map(int,input().split())))
B = tuple(A[i+1]-A[i]  for i in range(len(A)-1))
lim = math.ceil(len(B)/2)

L = 10**9+7
ans = 0
multi = cmb(N,K,mod)
for j in range(lim):
    front = j + 1
    back = N - front
    tmp_b = 0
    tmp_f = 0
    if front >= K:
        tmp_f = cmb(front,K,mod)
    if back >= K:
        tmp_b = cmb(back,K,mod)
    if j == (len(B)-1)/2:
        ans += (multi - tmp_b - tmp_f)*(B[j]) % L
    else:
        ans += (multi - tmp_b - tmp_f)*(B[j]+B[len(B)-1-j]) % L
print(ans%L)

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 = list(map(int,input().split()))
A = sorted(list(map(int,input().split())))
B = [A[i+1]-A[i]  for i in range(len(A)-1)]
lim = math.ceil(len(B)/2)

L = 10**9+7
ans = 0
multi = combinations_count(N,K)
for j in range(lim):
    front = j + 1
    back = N - front
    tmp_b = 0
    tmp_f = 0
    if front >= K:
        tmp_f = combinations_count(front,K) % L
    if back >= K:
        tmp_b = combinations_count(back,K) % L
    if j == (len(B)-1)/2:
        ans += (multi - tmp_b - tmp_f)*(B[j]) % L
    else:
        ans += (multi - tmp_b - tmp_f)*(B[j]+B[len(B)-1-j]) % L
print(ans%L)

Fixed submission:
import math

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+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 = list(map(int,input().split()))
A = sorted(tuple(map(int,input().split())))
B = tuple(A[i+1]-A[i]  for i in range(len(A)-1))
lim = math.ceil(len(B)/2)

L = 10**9+7
ans = 0
multi = cmb(N,K,mod)
for j in range(lim):
    front = j + 1
    back = N - front
    tmp_b = 0
    tmp_f = 0
    if front >= K:
        tmp_f = cmb(front,K,mod)
    if back >= K:
        tmp_b = cmb(back,K,mod)
    if j == (len(B)-1)/2:
        ans += (multi - tmp_b - tmp_f)*(B[j]) % L
    else:
        ans += (multi - tmp_b - tmp_f)*(B[j]+B[len(B)-1-j]) % L
print(ans%L)