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HITCON QUALS 2016 - Beelzemon (PPC 150)
#!/usr/bin/env python
#-*- coding:utf-8 -*-
from sock import Sock
def find_greedy(s):
a, b = [], []
sa = sb = 0
for x in sorted(s, reverse=True, key=abs):
if abs(sa + x - sb) < abs(sb + x - sa):
a.append(x)
sa += x
else:
b.append(x)
sb += x
while len(a) < len(b):
a.append(b.pop())
while len(a) > len(b):
b.append(a.pop())
if sum(a) == sum(b):
return a
return find_random(s, a, b)
def find_swap(a, b, sa, sb):
i = j = 0
best = (0, 0)
best_sa = -999999999999999
wanted_sa = (sa + sb) / 2
while i < len(a) and j < len(b):
test_sa = sa + b[j] - a[i]
if abs(test_sa - wanted_sa) < abs(best_sa - wanted_sa):
best = i, j
best_sa = test_sa
if test_sa < wanted_sa:
j += 1
elif test_sa > wanted_sa:
i += 1
elif test_sa == wanted_sa:
if i < len(a) - 1:
i += 1
else:
j += 1
return best
def move(a, i):
while i > 0 and a[i] < a[i-1]:
a[i-1], a[i] = a[i], a[i-1]
i -= 1
while i < len(a) - 1 and a[i] > a[i+1]:
a[i+1], a[i] = a[i], a[i+1]
i += 1
def find_random(s, a, b):
wanted = sum(s) / 2
sa, sb = sum(a), sum(b)
a = sorted(a)
b = sorted(b)
bad_itr = 0
prev = 0
while 1:
i, j = find_swap(a, b, sa, sb)
sa = sa - a[i] + b[j]
sb = sb - b[j] + a[i]
a[i], b[j] = b[j], a[i]
move(a, i)
move(b, j)
print n, k, len(s), "sa", sa, wanted, abs(sa - wanted)
if sa == wanted:
return a
if abs(sa - wanted) >= prev:
bad_itr += 1
if bad_itr == 10:
print "----"
break
else:
bad_itr = 0
prev = abs(sa - wanted)
f = Sock("52.198.217.117 6666")
itr = 0
while 1:
itr += 1
try:
res = f.read_line()
n, k = map(int, res.split())
except Exception as err:
print "Flag?", err, res, `f.buf`
quit()
print "#%d: %d %d" % (itr, n, k)
s = range(-2**n, 2**n)
if k & 1:
invmap = {x**k: x for x in s}
else:
invmap = {x**k: -abs(x) for x in s}
sk = sorted([x**k for x in s], key=abs)
print "solving.."
res = find_greedy(sk)
assert res, "failed :("
ans = []
for x in res:
ans.append(invmap[x])
if k % 2 == 0:
invmap[x] *= -1
assert sum(x**k for x in ans) == sum(sk) / 2
vec = " ".join(map(str, ans))
f.send_line(vec)
for n in xrange(1, 21):
for k in xrange(1, n + 1):
s = range(-2**n, 2**n)
sk = sorted([x**k for x in s],key=abs)
if k & 1:
invmap = {x**k: x for x in s}
else:
invmap = {x**k: -abs(x) for x in s}
print n, k
res = find_greedy(sk)
assert res, "failed :("
ans = []
for x in res:
ans.append(invmap[x])
if k % 2 == 0:
invmap[x] *= -1
assert sum(x**k for x in ans) == sum(sk) / 2
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