<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>

class Solution:
    def invalidTransactions(self, transactions: List[str]) -> List[str]:
        def parseTransaction(transaction):
            values = transaction.split(",")
            return values[0], int(values[1]), int(values[2]), values[3]

        # Record the transactions happen each time: t1: {name1: {city1, city2, ...}}
        t_trans = {}
        for transaction in transactions:
            name, t, amount, city = parseTransaction(transaction)

            if t not in t_trans:
                t_trans[t] = {name: {city}}
            else:
                # Add the city to the set
                if name in t_trans[t]:
                    t_trans[t][name].add(city)
                else:
                    t_trans[t][name] = {city}
        print(t_trans)

        # Validate the transactions
        res = []
        for transaction in transactions:
            name, t, amount, city = parseTransaction(transaction)

            # 1. The amount exceeds 1000
            if amount > 1000:
                res.append(transaction)
            # 2. Occurs within 60 minutes of another transaction with the same name in a different city
            else:
                for time in range(t-60, t+61):
                    if time in t_trans:
                        if name in t_trans[time]:
                            # Check: (1.) more than one city associated with the person
                            #        (2.) current transaction's city is different from the city where the person made the other transaction
                            if len(t_trans[time][name]) > 1 or next(iter(t_trans[time][name])) != city:
                                res.append(transaction)
                                break

        return res

"""
Time Complexity: O(N)
Space Complexity: O(N)
"""

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