<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) {
        // map name -> (map time -> (set -> city))
        unordered_map<string, unordered_map<int, unordered_set<string>>> mem;
        vector<string> invalidTransactions; // output

        for (string& trs : transactions) { // populate hash map
            string name, t, amount, city;
            stringstream ss(trs);
            getline(ss, name, ',');
            getline(ss, t, ',');
            getline(ss, amount, ','); // we dont use it but we need to move forward stringstream
            getline(ss, city, ','); // decode string
            
            int time = stoi(t); // change time to int
            if (!mem.count(name)) mem.insert({name, {}}); // create dicts if they dont exist
            if (!mem.at(name).count(time)) mem.at(name).insert({time, {}});

            mem.at(name).at(time).insert(city); // store all cities, if repeating doesnt insert, else it does
        }
        
        for (string& trs : transactions) { // check if transaction is valid
            string name, t, a, city;
            stringstream ss(trs);
            getline(ss, name, ',');
            getline(ss, t, ',');
            getline(ss, a, ',');
            getline(ss, city, ','); // decode string
            int time = stoi(t); // change to numbers
            int amount = stoi(a);
            
            if (amount > 1000) { // if its more than 1000 its not valid
                invalidTransactions.push_back(trs);
            } else for (int i = time - 60; i <= time + 60; i++) { // we check when i == time since we check if city is dif or if there more than one city in set
                if (!mem.at(name).count(i)) continue; // if i is not in times then continue

                if (mem.at(name).at(i).size() > 1 || !mem.at(name).at(i).count(city)) { // if theres more than one city in a set or curr city is different then its invalid
                    invalidTransactions.push_back(trs);
                    break;
                }
            } // ["alice,20,122,mtv","alice,20,120,mtv"] this should be allowed
        }

        return invalidTransactions;
        
    }
};
18900