<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 {
public:
    vector<string> invalidTransactions(vector<string>& transactions) {
        struct Txn {
            Txn(string str) : str(str), time(0), amount(0) {
                istringstream ss(str);
                getline(ss, name, ',');
                string tok;
                getline(ss, tok, ',');
                time = atoi(tok.c_str());
                getline(ss, tok, ',' );
                amount = atoi(tok.c_str());
                getline(ss, city, ',');
            }
            
            void operator=(const Txn& other) {
                str = other.str;
                name = other.name;
                time = other.time;
                amount = other.amount;
                city = other.city;
            }
        
            string str;
            string name;
            int time;
            int amount;
            string city;
        };
        
        unordered_map<string, vector<Txn>> txns;
        
        for (string& s : transactions) {
            Txn t(s);
            txns[t.name].push_back(t);
        }
        
        vector<string> invalid;
        
        for (auto& p : txns) {
            for (int i = 0; i < p.second.size(); ++i) {
                auto& t = p.second[i];
                if (t.amount > 1000)
                    invalid.push_back(t.str);
                else {
                    for (int j = 0; j < p.second.size(); ++j) {
                        if (i == j)
                            continue;
                        
                        auto& t2 = p.second[j];
                        if (t.city != t2.city && abs(t.time - t2.time) <= 60) {
                            invalid.push_back(t.str);
                            break;
                        }
                    }
                }
            }
        }
        
        return invalid;
    }
};
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