Buggy python submission (verdict: Time Limit Exceeded):
#%%
def count(a, k, n):
    l = []
    i, j, count = 0, n-1, 0
    while True:
        tmp = a[i] + a[j]
        if tmp >= k: 
            if j > 0:
                j -= 1
        elif tmp < k:
            l.append(n-j-1)
            count += n - j - 1
            i += 1
        if i >= n:
            break
        tmp = a[i] + a[j]
        if j == 0 and tmp >= k:
            l.append(n-j)
            count += n - j
            i += 1
        if i >= n:
            break
    return [count, l]

n, m = map(int, input().split())
a = list(map(int, input().split()))
a.sort()
l, r = 10**6, 1


while l - r > 1:
    mid = (l+r)//2
    if count(a, mid, n)[0] < m:
        l = mid
    elif count(a, mid, n)[0] > m:
        r = mid
    else :
        l = mid
        r = mid

ans = 0
if l == r:
    tmp = count(a, l, n)
    for i in range(n):
        ans += a[i] * tmp[1][i] * 2
else:
    p = count(a, l, n)
    q = count(a, r, n)
    check = -1
    for i in range(n):
        if p[1][i] != q[1][i]:
            check = i
            break
    ans += (a[i] + a[n - p[1][check] - 1]) * (m - p[0])
    tmp = count(a, l, n)
    for i in range(n):
        ans += a[i] * tmp[1][i] * 2
print(ans)



    


Fixed submission:
#%%
def count(a, k, n):
    l = []
    i, j, count = 0, n-1, 0
    while True:
        tmp = a[i] + a[j]
        if tmp >= k: 
            if j > 0:
                j -= 1
        elif tmp < k:
            l.append(n-j-1)
            count += n - j - 1
            i += 1
        if i >= n:
            break
        tmp = a[i] + a[j]
        if j == 0 and tmp >= k:
            l.append(n-j)
            count += n - j
            i += 1
        if i >= n:
            break
    return [count, l]

n, m = map(int, input().split())
a = list(map(int, input().split()))
a.sort()
l, r = 10**6, 1


while l - r > 1:
    mid = (l+r)//2
    if count(a, mid, n)[0] < m:
        l = mid
    elif count(a, mid, n)[0] > m:
        r = mid
    else :
        l = mid
        r = mid

ans = 0
if l == r:
    tmp = count(a, l, n)
    for i in range(n):
        ans += a[i] * tmp[1][i] * 2
else:
    p = count(a, l, n)
    q = count(a, r, n)
    check = -1
    for i in range(n):
        if p[1][i] != q[1][i]:
            check = i
            break
    ans += (a[i] + a[n - p[1][check] - 1]) * (m - p[0])
    tmp = count(a, l, n)
    for i in range(n):
        ans += a[i] * tmp[1][i] * 2
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
#%%
def count(a, k, n):
    l = []
    i, j, count = 0, n-1, 0
    while True:
        tmp = a[i] + a[j]
        if tmp >= k: 
            if j > 0:
                j -= 1
        elif tmp < k:
            l.append(n-j-1)
            if j < n - 1:
                j += 1
                count += n - j 
            else:
                count += n - j - 1
            i += 1
        if i >= n:
            break
        tmp = a[i] + a[j]
        if j == 0 and tmp >= k:
            l.append(n-j)
            count += n - j
            i += 1
        if i >= n:
            break
    return [count, l]

n, m = map(int, input().split())
a = list(map(int, input().split()))
a.sort()
l, r = 10**6, 1


while l - r > 1:
    mid = (l+r)//2
    if count(a, mid, n)[0] < m:
        l = mid
    elif count(a, mid, n)[0] > m:
        r = mid
    else :
        l = mid
        r = mid
    #print(l, r)

ans = 0
if l == r:
    tmp = count(a, l, n)
    for i in range(n):
        ans += a[i] * tmp[1][i] * 2
else:
    p = count(a, l, n)
    q = count(a, r, n)
    check = -1
    for i in range(n):
        if p[1][i] != q[1][i]:
            check = i
            break
    ans += (a[i] + a[n - p[1][check] - 1]) * (m - p[0])
    tmp = count(a, l, n)
    for i in range(n):
        ans += a[i] * tmp[1][i] * 2
print(ans)



    


Fixed submission:
#%%
def count(a, k, n):
    l = []
    i, j, count = 0, n-1, 0
    while True:
        tmp = a[i] + a[j]
        if tmp >= k: 
            if j > 0:
                j -= 1
        elif tmp < k:
            l.append(n-j-1)
            count += n - j - 1
            i += 1
        if i >= n:
            break
        tmp = a[i] + a[j]
        if j == 0 and tmp >= k:
            l.append(n-j)
            count += n - j
            i += 1
        if i >= n:
            break
    return [count, l]

n, m = map(int, input().split())
a = list(map(int, input().split()))
a.sort()
l, r = 10**6, 1


while l - r > 1:
    mid = (l+r)//2
    if count(a, mid, n)[0] < m:
        l = mid
    elif count(a, mid, n)[0] > m:
        r = mid
    else :
        l = mid
        r = mid

ans = 0
if l == r:
    tmp = count(a, l, n)
    for i in range(n):
        ans += a[i] * tmp[1][i] * 2
else:
    p = count(a, l, n)
    q = count(a, r, n)
    check = -1
    for i in range(n):
        if p[1][i] != q[1][i]:
            check = i
            break
    ans += (a[i] + a[n - p[1][check] - 1]) * (m - p[0])
    tmp = count(a, l, n)
    for i in range(n):
        ans += a[i] * tmp[1][i] * 2
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
#%%
def count(a, k, n):
    l = []
    i, j, count = 0, n-1, 0
    while True:
        tmp = a[i] + a[j]
        if tmp >= k: 
            if j > 0:
                j -= 1
        elif tmp < k:
            l.append(n-j-1)
            if j < n - 1:
                j += 1
                count += n - j 
            else:
                count += n - j - 1
            i += 1
        if i >= n:
            break
        tmp = a[i] + a[j]
        if j == 0 and tmp >= k:
            l.append(n-j)
            count += n - j
            i += 1
        if i >= n:
            break
    return [count, l]

n, m = map(int, input().split())
a = list(map(int, input().split()))
a.sort()
l, r = 10**6, 1


while l - r > 1:
    mid = (l+r)//2
    if count(a, mid, n)[0] < m:
        l = mid
    elif count(a, mid, n)[0] > m:
        r = mid
    else :
        l = r = mid

ans = 0
if l == r:
    tmp = count(a, l, n)
    for i in range(n):
        ans += a[i] * tmp[1][i] * 2
else:
    p = count(a, l, n)
    q = count(a, r, n)
    check = -1
    for i in range(n):
        if p[1][i] != q[1][i]:
            check = i
            break
    ans += (a[i] + a[n - p[1][i] - 1]) * (m - p[0])
    tmp = count(a, l, n)
    for i in range(n):
        ans += a[i] * tmp[1][i] * 2
print(ans)



    


Fixed submission:
#%%
def count(a, k, n):
    l = []
    i, j, count = 0, n-1, 0
    while True:
        tmp = a[i] + a[j]
        if tmp >= k: 
            if j > 0:
                j -= 1
        elif tmp < k:
            l.append(n-j-1)
            count += n - j - 1
            i += 1
        if i >= n:
            break
        tmp = a[i] + a[j]
        if j == 0 and tmp >= k:
            l.append(n-j)
            count += n - j
            i += 1
        if i >= n:
            break
    return [count, l]

n, m = map(int, input().split())
a = list(map(int, input().split()))
a.sort()
l, r = 10**6, 1


while l - r > 1:
    mid = (l+r)//2
    if count(a, mid, n)[0] < m:
        l = mid
    elif count(a, mid, n)[0] > m:
        r = mid
    else :
        l = mid
        r = mid

ans = 0
if l == r:
    tmp = count(a, l, n)
    for i in range(n):
        ans += a[i] * tmp[1][i] * 2
else:
    p = count(a, l, n)
    q = count(a, r, n)
    check = -1
    for i in range(n):
        if p[1][i] != q[1][i]:
            check = i
            break
    ans += (a[i] + a[n - p[1][check] - 1]) * (m - p[0])
    tmp = count(a, l, n)
    for i in range(n):
        ans += a[i] * tmp[1][i] * 2
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
#%%
def count(a, k, n):
    l = []
    i, j, count = 0, n-1, 0
    while True:
        tmp = a[i] + a[j]
        if tmp >= k: 
            if j > 0:
                j -= 1
        elif tmp < k:
            l.append(n-j-1)
            if j < n - 1:
                j += 1
                count += n - j 
            else:
                count += n - j - 1
            i += 1
        if i >= n:
            break
        tmp = a[i] + a[j]
        if j == 0 and tmp >= k:
            l.append(n-j)
            count += n - j
            i += 1
        if i >= n:
            break
    return [count, l]

n, m = map(int, input().split())
a = list(map(int, input().split()))
a.sort()
l, r = 10**6, 1


while l - r > 1:
    mid = (l+r)//2
    if count(a, mid, n)[0] < m:
        l = mid
    elif count(a, mid, n)[0] > m:
        r = mid
    else :
        l = r = mid

ans = 0
if l == r:
    for i in range(n):
        ans += a[i] * count(a, l, n)[1][i] * 2
else:
    p = count(a, l, n)
    q = count(a, r, n)
    check = -1
    for i in range(n):
        if p[1][i] != q[1][i]:
            check = i
            break
    ans += (a[i] + a[n - p[1][i] - 1]) * (m - p[0])
    for i in range(n):
        ans += a[i] * count(a, l, n)[1][i] * 2
print(ans)



    


Fixed submission:
#%%
def count(a, k, n):
    l = []
    i, j, count = 0, n-1, 0
    while True:
        tmp = a[i] + a[j]
        if tmp >= k: 
            if j > 0:
                j -= 1
        elif tmp < k:
            l.append(n-j-1)
            count += n - j - 1
            i += 1
        if i >= n:
            break
        tmp = a[i] + a[j]
        if j == 0 and tmp >= k:
            l.append(n-j)
            count += n - j
            i += 1
        if i >= n:
            break
    return [count, l]

n, m = map(int, input().split())
a = list(map(int, input().split()))
a.sort()
l, r = 10**6, 1


while l - r > 1:
    mid = (l+r)//2
    if count(a, mid, n)[0] < m:
        l = mid
    elif count(a, mid, n)[0] > m:
        r = mid
    else :
        l = mid
        r = mid

ans = 0
if l == r:
    tmp = count(a, l, n)
    for i in range(n):
        ans += a[i] * tmp[1][i] * 2
else:
    p = count(a, l, n)
    q = count(a, r, n)
    check = -1
    for i in range(n):
        if p[1][i] != q[1][i]:
            check = i
            break
    ans += (a[i] + a[n - p[1][check] - 1]) * (m - p[0])
    tmp = count(a, l, n)
    for i in range(n):
        ans += a[i] * tmp[1][i] * 2
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
#%%
def count(a, k, n):
    l = []
    i, j, count = 0, n-1, 0
    while True:
        tmp = a[i] + a[j]
        if tmp >= k: 
            if j > 0:
                j -= 1
        elif tmp < k:
            l.append(n-j-1)
            if j < n - 1:
                j += 1
                count += n - j 
            else:
                count += n - j - 1
            i += 1
        if i >= n:
            break
        tmp = a[i] + a[j]
        if j == 0 and tmp >= k:
            l.append(n-j)
            count += n - j
            i += 1
        if i >= n:
            break
    return [count, l]

n, m = map(int, input().split())
a = list(map(int, input().split()))
a.sort()
l, r = 10**6, 1


while l - r > 1:
    mid = (l+r)//2
    if count(a, mid, n)[0] < m:
        l = mid
    elif count(a, mid, n)[0] > m:
        r = mid
    else :
        l = r = mid

ans = 0
if l == r:
    for i in range(n):
        ans += a[i] * count(a, l, n)[1][i] * 2
else:
    p = count(a, l, n)
    q = count(a, r, n)
    check = -1
    for i in range(n):
        if p[1][i] != q[1][i]:
            check = i
            break
    ans += (a[i] + a[n - p[1][i] - 1]) * (m - p[0])
    for i in range(n):
        ans += a[i] * count(a, l, n)[1][i] * 2
print(ans)



    


Fixed submission:
#%%
def count(a, k, n):
    l = []
    i, j, count = 0, n-1, 0
    while True:
        tmp = a[i] + a[j]
        if tmp >= k: 
            if j > 0:
                j -= 1
        elif tmp < k:
            l.append(n-j-1)
            count += n - j - 1
            i += 1
        if i >= n:
            break
        tmp = a[i] + a[j]
        if j == 0 and tmp >= k:
            l.append(n-j)
            count += n - j
            i += 1
        if i >= n:
            break
    return [count, l]

n, m = map(int, input().split())
a = list(map(int, input().split()))
a.sort()
l, r = 10**6, 1


while l - r > 1:
    mid = (l+r)//2
    if count(a, mid, n)[0] < m:
        l = mid
    elif count(a, mid, n)[0] > m:
        r = mid
    else :
        l = mid
        r = mid

ans = 0
if l == r:
    tmp = count(a, l, n)
    for i in range(n):
        ans += a[i] * tmp[1][i] * 2
else:
    p = count(a, l, n)
    q = count(a, r, n)
    check = -1
    for i in range(n):
        if p[1][i] != q[1][i]:
            check = i
            break
    ans += (a[i] + a[n - p[1][check] - 1]) * (m - p[0])
    tmp = count(a, l, n)
    for i in range(n):
        ans += a[i] * tmp[1][i] * 2
print(ans)