<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]:
        # group trans by user
        # sort transactions for each user
        # find the ones > 1000
        # find ones that a too close to each other
        
        def parse(trans):
            name, t, amount, city = trans.split(',')
            return [name, int(t), int(amount), city]
        
        user_map = defaultdict(list)
        for trans in transactions:
            name, t, am, city = parse(trans)
            user_map[name].append([name, t, am, city])
        
        def to_str(trans):
            return ','.join([str(item) for item in trans])
        
        def add_if_not_already(lst, trans, idx, added):
            if idx not in added:
                lst.append(to_str(trans))
                added.add(idx)
                
        invalid = []
        for name, trans_lst in user_map.items():
            trans_lst.sort(key=lambda x: x[1])
            added = set()
            for idx, trans in enumerate(trans_lst):
                if trans[2] > 1000:
                    add_if_not_already(invalid, trans, idx, added)
                
                for j in range(idx-1, -1, -1):
                    if trans_lst[j][-1] != trans[-1] and trans[1] - trans_lst[j][1] <= 60: #not the same city and within 60 mins
                        add_if_not_already(invalid, trans_lst[j], j, added)
                        add_if_not_already(invalid, trans, idx, added)
                        
                
        return invalid
87