<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>

struct Transaction {
    int time;
    int amount;
    string city;

    string toString() {
        ostringstream oss;
        oss << time << "," << amount << "," << city;
        return oss.str();
    }
};
class Solution {
public:
    vector<string> invalidTransactions(vector<string>& transactions) {
        vector<struct Transaction> v;
        map<string, vector<struct Transaction>> graph;

        vector<string> ret;
        for (auto& t : transactions) {
            stringstream ss(t);
            string name, time, amount, city;
            getline(ss, name, ',');
            getline(ss, time, ',');
            getline(ss, amount, ',');
            getline(ss, city, ',');
            graph[name].push_back({stoi(time), stoi(amount), city});
        }

        for (auto& kv : graph) {
            sort(kv.second.begin(), kv.second.end(),
                 [](const auto& a, const auto& b) { return a.time < b.time; });

            vector<bool> invalid(kv.second.size(), false);
            for (int i = kv.second.size() - 1; i >= 0; --i) {
                for(int j = i - 1; j >= 0 ; --j) {
                    if (kv.second[i].time <= kv.second[j].time + 60 &&
                        kv.second[i].city != kv.second[j].city) {
                        invalid[i] = true;
                        invalid[j] = true;
                    }
                }
                if (kv.second[i].amount > 1000 ) {
                    invalid[i] = true;
                }
                if (invalid[i]) {
                    ostringstream oss;
                    oss << kv.first << "," << kv.second[i].toString();
                    ret.push_back(oss.str());
                }
            }
        }

        return ret;
    }
};
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