LeetCode-in-Java

1169. Invalid Transactions

Medium

A transaction is possibly invalid if:

• the amount exceeds $1000, or;
• if it occurs within (and including) 60 minutes of another transaction with the same name in a different city.

You are given an array of strings transaction where transactions[i] consists of comma-separated values representing the name, time (in minutes), amount, and city of the transaction.

Return a list of transactions that are possibly invalid. You may return the answer in any order.

Example 1:

Input: transactions = [“alice,20,800,mtv”,”alice,50,100,beijing”]

Output: [“alice,20,800,mtv”,”alice,50,100,beijing”]

Explanation: 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.

Example 2:

Input: transactions = [“alice,20,800,mtv”,”alice,50,1200,mtv”]

Output: [“alice,50,1200,mtv”]

Example 3:

Input: transactions = [“alice,20,800,mtv”,”bob,50,1200,mtv”]

Output: [“bob,50,1200,mtv”]

Constraints:

• transactions.length <= 1000
• Each transactions[i] takes the form "{name},{time},{amount},{city}"
• Each {name} and {city} consist of lowercase English letters, and have lengths between 1 and 10.
• Each {time} consist of digits, and represent an integer between 0 and 1000.
• Each {amount} consist of digits, and represent an integer between 0 and 2000.

Solution

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class Solution {
    private static class Transaction {
        String name;
        int time;
        int amount;
        String city;

        Transaction(String trans) {
            String[] s = trans.split(",");
            name = s[0];
            time = Integer.parseInt(s[1]);
            amount = Integer.parseInt(s[2]);
            city = s[3];
        }
    }

    public List<String> invalidTransactions(String[] input) {
        List<String> res = new ArrayList<>();
        if (input == null || input.length == 0) {
            return res;
        }
        Map<String, List<Transaction>> map = new HashMap<>();
        for (String s : input) {
            Transaction trans = new Transaction(s);
            if (!map.containsKey(trans.name)) {
                map.put(trans.name, new ArrayList<>());
            }
            map.get(trans.name).add(trans);
        }
        for (String s : input) {
            Transaction trans = new Transaction(s);
            if (!isValid(trans, map)) {
                res.add(s);
            }
        }
        return res;
    }

    private boolean isValid(Transaction transaction, Map<String, List<Transaction>> map) {
        if (transaction.amount > 1000) {
            return false;
        }
        for (Transaction s : map.get(transaction.name)) {
            if (Math.abs(s.time - transaction.time) <= 60 && !s.city.equals(transaction.city)) {
                return false;
            }
        }
        return true;
    }
}

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