<p>A transaction is possibly invalid if:</p>

<ul>
	<li>the amount exceeds <code>$1000</code>, or;</li>
	<li>if it occurs within (and including) <code>60</code> minutes of another transaction with the <strong>same name</strong> in a <strong>different city</strong>.</li>
</ul>

<p>You are given an array of strings <code>transaction</code> where <code>transactions[i]</code> consists of comma-separated values representing the name, time (in minutes), amount, and city of the transaction.</p>

<p>Return a list of <code>transactions</code> that are possibly invalid. You may return the answer in <strong>any order</strong>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> transactions = [&quot;alice,20,800,mtv&quot;,&quot;alice,50,100,beijing&quot;]
<strong>Output:</strong> [&quot;alice,20,800,mtv&quot;,&quot;alice,50,100,beijing&quot;]
<strong>Explanation:</strong> The first transaction is invalid because the second transaction occurs within a difference of 60 minutes, have the same name and is in a different city. Similarly the second one is invalid too.</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> transactions = [&quot;alice,20,800,mtv&quot;,&quot;alice,50,1200,mtv&quot;]
<strong>Output:</strong> [&quot;alice,50,1200,mtv&quot;]
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> transactions = [&quot;alice,20,800,mtv&quot;,&quot;bob,50,1200,mtv&quot;]
<strong>Output:</strong> [&quot;bob,50,1200,mtv&quot;]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>transactions.length &lt;= 1000</code></li>
	<li>Each <code>transactions[i]</code> takes the form <code>&quot;{name},{time},{amount},{city}&quot;</code></li>
	<li>Each <code>{name}</code> and <code>{city}</code> consist of lowercase English letters, and have lengths between <code>1</code> and <code>10</code>.</li>
	<li>Each <code>{time}</code> consist of digits, and represent an integer between <code>0</code> and <code>1000</code>.</li>
	<li>Each <code>{amount}</code> consist of digits, and represent an integer between <code>0</code> and <code>2000</code>.</li>
</ul>

from collections import defaultdict
class Transaction:
    def __init__(self, trxn: str):
        self.name, self.time, self.amount, self.city = trxn.split(",")
        self.trxn = trxn
        self.is_invalid = False
        self.time = int(self.time)
        self.amount = int(self.amount)
    
    

class Solution:
    def invalidTransactions(self, transactions: List[str]) -> List[str]:
        cache = defaultdict(lambda: defaultdict(set))

        transactions = [Transaction(trxn) for trxn in transactions]
        
        for trxn in transactions:
            cache[trxn.name][trxn.time].add(trxn.city)
        
        for trxn in transactions:
            if trxn.amount > 1000:
                trxn.is_invalid = True
        
        for trxn in transactions:
            if trxn.name not in cache:
                continue
            for t in range(trxn.time - 60, trxn.time + 60):
                if t not in cache[trxn.name]:
                    continue
                if len(cache[trxn.name][t]) > 1 or trxn.city not in cache[trxn.name][t]:
                    trxn.is_invalid = True
        
        return [trxn.trxn for trxn in transactions if trxn.is_invalid]
                
                    
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