<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 {
    struct Transaction{
        string name;
        int time;
        int amount;
        string city;
        bool invalid = false;
        Transaction(string input){
            auto ss = stringstream(input);
            string temp;
            getline(ss, name, ',');
            getline(ss, temp, ',');
            time = stoi(temp);
            getline(ss, temp, ',');
            amount = stoi(temp);
            getline(ss, city, ',');
        }

        string toString(){
            return name + ',' + to_string(time) + ',' + to_string(amount) + ',' + city;
        }

        bool operator<(const Transaction& other){
            return this->time < other.time;
        }
    };
public:
    vector<string> invalidTransactions(vector<string>& transactions) {
        vector<string> ans;
        unordered_map<string, vector<Transaction>> data;
        for(int i = 0; i < transactions.size(); ++i){
            Transaction t(transactions[i]);
            data[t.name].push_back(t);
        }
        for(auto iter = data.begin(); iter != data.end(); ++iter){
            vector<Transaction>& list = iter->second;
            sort(list.begin(), list.end()); 
            for(int left = 0; left < list.size()-1; ++left){
                if(list[left].amount > 1000 && !list[left].invalid){
                    ans.push_back(list[left].toString());
                    list[left].invalid = true;
                }
                for(int right = left+1; right < list.size(); ++right){
                    if(list[right].time - list[left].time > 60){
                        break;
                    }
                    if(list[right].city != list[left].city){
                        if(!list[left].invalid){
                            ans.push_back(list[left].toString());
                            list[left].invalid = true;
                        }
                        if(!list[right].invalid){
                            ans.push_back(list[right].toString());
                            list[right].invalid = true;
                        }
                    }
                }
            }
            if(!list[list.size()-1].invalid && list[list.size()-1].amount > 1000){
                ans.push_back(list[list.size() - 1].toString());
            }
        }
        return vector<string>(ans.begin(), ans.end());
    }
};
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