Made defragmentation work
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@ -1,6 +1,11 @@
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import random, heapq
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# Assuming `online` is the set of users that is online, find a path to
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# send `amount` coins from `frm` to `to` through `coins` where each
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# step along the path is between users that have adjacent fragments.
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# A transfer done in this way does not contribute to fragmentation.
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def find_path(coins, frm, to, amount, online):
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# Determine who is whose neighbor
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neighbor_map = {}
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for i in range(amount, len(coins) - amount + 1):
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if coins[i-1] != coins[i]:
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@ -9,9 +14,10 @@ def find_path(coins, frm, to, amount, online):
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neighbor_map[coins[i-1]] = list(set(neighbor_map.get(coins[i-1], []) + [coins[i]]))
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if coins[i:i+amount] == [coins[i]] * amount:
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neighbor_map[coins[i]] = list(set(neighbor_map.get(coins[i], []) + [coins[i-1]]))
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# Search for the path
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parents = {frm: None}
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q = [(0, frm)]
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while len(q) > 0:
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while q:
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dist, sender = heapq.heappop(q)
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neighbors = neighbor_map.get(sender, [])
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for n in neighbors:
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@ -25,21 +31,7 @@ def find_path(coins, frm, to, amount, online):
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return o
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return False
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def mk_fragmented_shuffle(coins, owners, shuffs):
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L = [(i * owners)//coins for i in range(coins)]
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for i in range(shuffs):
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x1 = random.randrange(n)
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x2 = random.randrange(n)
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value = int(min(n - x1, n - x2, abs(x2 - x1)) ** random.random())
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L[x1:x1+value], L[x2:x2+value] = L[x2:x2+value], L[x1:x1+value]
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return L
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def mk_shuffle(n):
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L = list(range(1, n+1))
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random.shuffle(L)
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return ','.join([str(x) for x in L])
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# How many fragments are in this set of coins?
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def fragments(vals):
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tot = 1
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for i in range(1, len(vals)):
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@ -47,6 +39,8 @@ def fragments(vals):
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tot += 1
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return tot
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# Send `amt` coins from `frm` to `to`. Increases fragmentation by
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# maximum 1
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def send_coins(coins, frm, to, amt):
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coins_to_send = amt
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for i in range(len(coins)):
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@ -57,45 +51,96 @@ def send_coins(coins, frm, to, amt):
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return True
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return False
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def shunt_coins(coins, frm, to, amt):
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# Get the concrete range to transfer if we are transfering `amt`
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# coins from `frm` to `to` (must be neighboring fragments)
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def get_coin_shunt(coins, frm, to, amt):
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i = 1
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while i < len(coins):
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while i < len(coins) and not((coins[i-1] == frm and coins[i] == to) or (coins[i-1] == to and coins[i] == frm)):
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L = len(coins)
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while i < L:
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while i < L and coins[i] not in (frm, to):
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i += 1
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if coins[i-amt:i] == [frm] * amt:
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if not((coins[i-1] == frm and coins[i] == to) or (coins[i-1] == to and coins[i] == frm)):
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i += 1
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continue
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if coins[i-amt:i] == [frm] * amt and coins[i] == to:
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coins[i-amt:i] = [to] * amt
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return True
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if coins[i:i+amt] == [frm] * amt:
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return (i-amt, i, to)
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if coins[i:i+amt] == [frm] * amt and coins[i-1] == to:
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coins[i:i+amt] = [to] * amt
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return True
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return (i, i+amt, to)
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i += 1
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return False
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userz = 100
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# Find the largest slice controlled by `acct`
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def maxslice(coins, acct):
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maxsz = 0
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sz = 0
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for i in range(len(coins)):
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if coins[i] == acct:
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sz += 1
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maxsz = max(sz, maxsz)
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else:
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sz = 0
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return maxsz
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# Count the number of coins and the number of fragments
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# held by each user
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def count_coins_and_fragments(coins):
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user_count = max(coins) + 1
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coin_count = [0] * user_count
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frag_count = [0] * user_count
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for i in range(len(coins)):
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coin_count[coins[i]] += 1
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if i > 0 and coins[i] != coins[i-1]:
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frag_count[coins[i]] += 1
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return coin_count, frag_count
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userz = 25
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coinz = 50000
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part_online = 0.2
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c = [(i*userz)//coinz for i in range(coinz)]
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for i in range(25000):
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if i%10 == 0:
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print(fragments(c))
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part_online = 0.1
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initial_fragments_per_user = 100
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ordering = list(range(userz)) * initial_fragments_per_user
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random.shuffle(ordering)
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c = [ordering[i * len(ordering) //coinz] for i in range(coinz)]
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balances = count_coins_and_fragments(c)[0]
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for i in range(250000):
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if i%100 == 0:
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print(i, fragments(c))
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# if i%2000 == 0:
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# coin_count, frag_count = count_coins_and_fragments(c)
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# print(sorted(zip(coin_count, frag_count)))
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# Randomly select sender, recipient and amount
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frm = random.randrange(userz)
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to = random.randrange(userz)
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# amount = int(c.count(frm) ** random.random())
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amount = random.randrange(1, 11)
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if frm == to or amount == 0:
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if frm == to:
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continue
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path = find_path(c, frm, to, amount+1, [i for i in range(userz) if random.random() < part_online or i in (frm, to)])
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#pre_balance = (c.count(frm), c.count(to))
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pre_balance = balances[frm]
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amount = random.randrange(1, 1 + int(pre_balance ** random.random())) if pre_balance >= 2 else pre_balance
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full_amount = amount
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# print("Paying %d coins from %d to %d" % (amount, frm, to))
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# Randomly select the users that are online
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online = [i for i in range(userz) if random.random() < part_online or i in (frm, to)]
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while amount > 0:
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maxpay = maxslice(c, frm)
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pay_this_round = min(amount, maxpay)
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path = find_path(c, frm, to, pay_this_round, online)
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if path:
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print(path)
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#print("Found path for %d coins (%d hops)" % (pay_this_round, len(path)-1))
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assert path[0] == frm
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assert path[-1] == to
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shunts = []
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for i in range(1, len(path)):
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assert shunt_coins(c, path[i-1], path[i], amount)
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shunts.append(get_coin_shunt(c, path[i-1], path[i], pay_this_round))
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assert shunts[-1]
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for shunt in shunts:
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start, end, to = shunt
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c[start:end] = [to] * (end-start)
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amount -= pay_this_round
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else:
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print('no path')
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assert amount <= c.count(frm)
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# print('No path, paying remaining amount %d via fragmentation' % amount)
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# print('%d fragments' % fragments(c))
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assert send_coins(c, frm, to, amount)
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#post_balance = (c.count(frm), c.count(to))
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#assert pre_balance[0] - post_balance[0] == amount
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#assert post_balance[1] - pre_balance[1] == amount
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break
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balances[frm] -= full_amount
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balances[to] += full_amount
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