Problem p02616 (python)

Fixed submission:
mod = 10**9 + 7

def sgn(v):
    return (v > 0) - (v < 0)

def compute_answer():
    v.sort(key=abs, reverse=True)
    prod = 1
    sg = 1
    for a in xrange(k):
        prod *= v[a]
        prod %= mod
        sg *= sgn(v[a])

    if sg >= 0:
        return prod

    if max(v) <= 0:
        prod = 1
        for a in xrange(-k,0):
            prod *= v[a]
            prod %= mod
        return prod

    def find_pair(comp):
        i = k-1
        while i >= 0 and comp(v[i]): i -= 1
        j = k
        while j < n and not comp(v[j]): j += 1
        if j == n: j = i
        return i, j
    i, j = find_pair(lambda w: w >= 0)
    I, J = find_pair(lambda w: w <= 0)
    if I >= 0 and v[j] * v[I] < v[i] * v[J]:
        i = I
        j = J

    prod = v[j]
    for a in xrange(k):
        if a != i:
            prod *= v[a]
            prod %= mod
    return prod

n, k = map(int, raw_input().strip().split())
v = map(int, raw_input().strip().split())
print compute_answer()

Buggy submission (verdict: Runtime Error):
mod = 10**9 + 7

def sgn(v):
    return (v > 0) - (v < 0)

def compute_answer():
    v.sort(key=abs, reverse=True)
    prod = 1
    sg = 1
    for a in xrange(k):
        prod *= v[a]
        prod %= mod
        sg *= sgn(v[a])

    if sg >= 0:
        return prod

    if max(v) <= 0:
        prod = 1
        for a in xrange(-k,0):
            prod *= v[a]
            prod %= mod
        return prod

    def find_pair(comp):
        i = k-1
        while i >= 0 and comp(v[i]): i -= 1
        j = k
        while j < n and not comp(v[j]): j += 1
        if j == n: j = i
        return i, j
    i, j = find_pair(lambda w: w >= 0)
    I, J = find_pair(lambda w: w <= 0)
    if I >= 0 and v[j] * v[I] < v[i] * v[J]:
        i = I
        j = J

    prod = v[j]
    for a in xrange(k):
        if a != i:
            prod *= v[a]
            prod %= mod
    return prod

for cas in xrange(input()):
    n, k = map(int, raw_input().strip().split())
    v = map(int, raw_input().strip().split())
    print compute_answer()

Buggy submission (verdict: Runtime Error):
mod = 10**9 + 7

def sgn(v):
    return (v > 0) - (v < 0)

def compute_answer():
    v.sort(key=abs, reverse=True)
    prod = 1
    sg = 1
    for a in xrange(k):
        prod *= v[a]
        prod %= mod
        sg *= sgn(v[a])

    if sg >= 0:
        return prod

    if max(v) <= 0:
        prod = 1
        for a in xrange(-k,0):
            prod *= v[a]
            prod %= mod
        return prod

    def find_pair(comp):
        i = k-1
        while i >= 0 and comp(v[i]): i -= 1
        j = k
        while j < n and not comp(v[j]): j += 1
        if j == n: j = i
        return i, j
    i, j = find_pair(lambda w: w >= 0)
    I, J = find_pair(lambda w: w <= 0)
    if I >= 0 and v[j] * v[I] < v[i] * v[J]:
        i = I
        j = J

    prod = v[j]
    for a in xrange(k):
        if a != i:
            prod *= v[a]
            prod %= mod
    return prod

for cas in xrange(input()):
    n, k = map(int, raw_input().strip().split())
    v = map(int, raw_input().strip().split())
    print compute_answer()

Buggy submission (verdict: Runtime Error):
mod = 10**9 + 7

def sgn(v):
    return (v > 0) - (v < 0)

def compute_answer():
    v.sort(key=abs, reverse=True)
    prod = 1
    sg = 1
    for a in xrange(k):
        prod *= v[a]
        prod %= mod
        sg *= sgn(v[a])

    if sg >= 0:
        return prod

    if max(v) <= 0:
        prod = 1
        for a in xrange(-k,0):
            prod *= v[a]
            prod %= mod
        return prod

    def find_pair(comp):
        i = k-1
        while i >= 0 and comp(v[i]): i -= 1
        j = k
        while j < n and not comp(v[j]): j += 1
        if j == n: j = i
        return i, j
    i, j = find_pair(lambda w: w >= 0)
    I, J = find_pair(lambda w: w <= 0)
    if I >= 0 and v[j] * v[I] < v[i] * v[J]:
        i = I
        j = J

    prod = v[j]
    for a in xrange(k):
        if a != i:
            prod *= v[a]
            prod %= mod
    return prod

for cas in xrange(1):
    n, k = map(int, raw_input().strip().split())
    v = map(int, raw_input().strip().split())
    print compute_answer()