interview2

package solutions;

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

public class transfers {
    public static List<String> transferBalances(List<String> balances) {
        Map<Character, Integer> map = new HashMap<>();
        for (String balance: balances) {
            char sourceBank = balance.charAt(0);
            char destBank = balance.charAt(1);
            int amount = Integer.parseInt(balance.substring(2));
            map.put(sourceBank, map.getOrDefault(sourceBank, 0) - amount);
            map.put(destBank, map.getOrDefault(destBank, 0) + amount);
        }

        char initialCentralBank = balances.get(0).charAt(0);
        char centralBank = selectCentralBank(map, initialCentralBank);
        List<String> res = new ArrayList<>();
        for (Map.Entry<Character, Integer> entry: map.entrySet()) {
            if (entry.getKey() == centralBank) {
                continue;
            }

            StringBuilder sb = new StringBuilder();
            if (entry.getValue() < 0) {
                sb.append(entry.getKey()).append(centralBank).append(-1 * entry.getValue());
            } else if (entry.getValue() > 0) {
                sb.append(centralBank).append(entry.getKey()).append(entry.getValue());
            }
            res.add(sb.toString());
        }
        return res;
    }

    public static char selectCentralBank(Map<Character, Integer> map, char initialCentralBank) {
        char res = initialCentralBank;
        int maxAbsAmount = map.get(initialCentralBank);
        for (Map.Entry<Character, Integer> entry: map.entrySet()) {
            if (Math.abs(entry.getValue()) >  maxAbsAmount) {
                maxAbsAmount = Math.abs(entry.getValue());
                res = entry.getKey();
            }
        }
        return res;
    }

    public static void main(String[] args) {
        List<String> balances = new ArrayList<>();
        balances.add("AB1");
        balances.add("BC1"); // AC1 XY1
        balances.add("XY1");
//      balances.add("DC1");  // DC1
//      balances.add("BC100"); // A0 B0 C0
        List<String> res = transferBalances(balances);
        for (String val: res) {
            System.out.println(val); // AB10    AC10000
        }
    }
}