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Leetcode1169-invalidTransactions

Posted on Edited on In Views: Valine:
Solution Report of LeetCode Acceptted

Description

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.
Each transaction string transactions[i] consists of comma separated values representing the name, time (in minutes), amount, and city of the transaction.

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

Example

Example 1:

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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:
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Input: transactions = ["alice,20,800,mtv","alice,50,1200,mtv"]
Output: ["alice,50,1200,mtv"]

Example 3:
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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

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// Map
// Key: Name
// Value: List of {time, amount, city}
// 
// once new transaction come under one name
// check amount first, 
// then if in differnt cities, check if time invalid 

// Define a custmized class to store history imfomation, it can save time of spliting each time

class Solution {
    class Transaction{
        String name;
        int time;
        String city;
        String trans;
        public Transaction(String name, int time, String city, String trans){
            this.name = name;
            this.time = time;
            this.city = city;
            this.trans = trans;
        }
    }
    public List<String> invalidTransactions(String[] transactions) {
        HashMap<String, List<Transaction>> map = new HashMap<>();
        if (transactions == null || transactions.length == 0) return new ArrayList<>();
        
        HashSet<String> invalid = new HashSet<>();
        for (String transaction: transactions){
            String[] cur = transaction.split(",");
            String name = cur[0];
            int time = Integer.valueOf(cur[1]);
            int amount = Integer.valueOf(cur[2]);
            String city = cur[3];
//             Check if amount invalid
            if (amount > 1000)
                invalid.add(transaction);
            
            if (!map.containsKey(name))
                map.put(name, new ArrayList<Transaction>());
            
            for (Transaction history: map.get(name)){
//                 Check if in different cities
                if (!history.city.equals(cur[3])){
//                     Check if time invalid
                    if (Math.abs(time - history.time) <= 60){
                        invalid.add(transaction);
                        invalid.add(history.trans);
                    }
                }
            }
            map.get(name).add(new Transaction(name, time, city, transaction));
        }
        
        return new ArrayList<String>(invalid);
    }
}