<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) {
        vector<string>ans;
        vector<string>aux;
        unordered_map<string, vector<pair<int, string>>>mp;
        unordered_map<string, vector<int>>mp1;
        unordered_set<int>st;
        for (int i = 0; i < transactions.size(); i++) {
            string name = "";
            int j = 0;
            while(j < transactions[i].size() && transactions[i][j] != ',')
                name += transactions[i][j++];
            int time = 0;
            j++;
            while(j < transactions[i].size() && transactions[i][j] != ',') {
                time *= 10;
                time += transactions[i][j++] - '0';
            }
            j++;
            int amount = 0;
            while(j < transactions[i].size() && transactions[i][j] != ',') {
                amount *= 10;
                amount += transactions[i][j++] - '0';
            }
            j++;
            string city = "";
            while(j < transactions[i].size() && transactions[i][j] != ',')
                city += transactions[i][j++];
            if (amount > 1000) {
                ans.push_back(transactions[i]);
                st.insert(i);
            } 
                string temp = name + "_" + to_string(time) + "_" + city;
                mp1[temp].push_back(i);
                mp[name].push_back({time, city});
            
        }
        for (auto x : mp) {
            for (int j = 0; j < x.second.size(); j++) {
                for (int k = 0; k < x.second.size(); k++) {
                    if (k != j) {
                        if (abs(x.second[j].first - x.second[k].first) <= 60 && x.second[j].second != x.second[k].second) {
                            string temp = x.first + "_" + to_string(x.second[j].first) + "_" + x.second[j].second;
                            if (mp1.find(temp) != mp1.end()) {
                            int ind = mp1[temp].back();
                            mp1[temp].pop_back();
                            if (!mp1[temp].size())
                                mp1.erase(temp);
                            if (st.find(ind) == st.end()) {
                                st.insert(ind);
                                ans.push_back(transactions[ind]);
                            }
                            }
                            temp = x.first + "_" + to_string(x.second[k].first) + "_" + x.second[k].second;
                            if (mp1.find(temp) != mp1.end()) {
                            int ind = mp1[temp].back();
                            mp1[temp].pop_back();
                            if (!mp1[temp].size())
                                mp1.erase(temp);
                            if (st.find(ind) == st.end()) {
                                st.insert(ind);
                                ans.push_back(transactions[ind]);
                            }
                            }
                        }
                    }
                }
            }
        }
        return ans;
    }
};
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