def winningLotteryTicket(tickets): # Convert each ticket to a bitmask freq = {} FULL_MASK = (1 << 10) - 1 # 1023 = 0b1111111111

for ticket in tickets:
    mask = 0
    for digit in ticket:
        mask |= 1 << int(digit)
    freq[mask] = freq.get(mask, 0) + 1

masks = list(freq.keys())
count = 0

for i in range(len(masks)):
    for j in range(i, len(masks)):
        if (masks[i] | masks[j]) == FULL_MASK:
            if i == j:
                # pairs from the same mask: nC2 = n*(n-1)//2
                count += freq[masks[i]] * (freq[masks[i]] - 1) // 2
            else:
                # pairs from different masks
                count += freq[masks[i]] * freq[masks[j]]
return count