2 files changed, 134 insertions, 0 deletions
diff --git a/src/main/PhoneBook.java b/src/main/PhoneBook.java
new file mode 100644
index 0000000..66bf471
--- /dev/null
+++ b/src/main/PhoneBook.java
@@ -0,0 +1,108 @@
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.StringTokenizer;
+
+public class PhoneBook {
+
+    private FastScanner in = new FastScanner();
+    // Keep list of all existing (i.e. not deleted yet) contacts.
+    private List<Contact> contacts = new ArrayList<>();
+
+    public static void main(String[] args) {
+        new PhoneBook().processQueries();
+    }
+
+    private Query readQuery() {
+        String type = in.next();
+        int number = in.nextInt();
+        if (type.equals("add")) {
+            String name = in.next();
+            return new Query(type, name, number);
+        } else {
+            return new Query(type, number);
+        }
+    }
+
+    private void writeResponse(String response) {
+        System.out.println(response);
+    }
+
+
+    private void processQuery(Query query) {
+        switch (query.type) {
+            case "add":
+                contacts.get(query.number).name = query.name;
+                break;
+            case "del":
+                contacts.get(query.number).name = "not found";
+                break;
+            default:
+                writeResponse(contacts.get(query.number).name);
+                break;
+        }
+    }
+
+    private void processQueries() {
+        for (int i = 0; i < 10000000; i++) {
+           contacts.add(new Contact("not found", i));
+        }
+        int queryCount = in.nextInt();
+        for (int i = 0; i < queryCount; ++i)
+            processQuery(readQuery());
+    }
+
+    static class Contact {
+        String name;
+        int number;
+
+        Contact(String name, int number) {
+            this.name = name;
+            this.number = number;
+        }
+    }
+
+    static class Query {
+        String type;
+        String name;
+        int number;
+
+        Query(String type, String name, int number) {
+            this.type = type;
+            this.name = name;
+            this.number = number;
+        }
+
+        Query(String type, int number) {
+            this.type = type;
+            this.number = number;
+        }
+    }
+
+    class FastScanner {
+        BufferedReader br;
+        StringTokenizer st;
+
+        FastScanner() {
+            br = new BufferedReader(new InputStreamReader(System.in));
+        }
+
+        String next() {
+            while (st == null || !st.hasMoreTokens()) {
+                try {
+                    st = new StringTokenizer(br.readLine());
+                } catch (IOException e) {
+                    e.printStackTrace();
+                }
+            }
+            return st.nextToken();
+        }
+
+        int nextInt() {
+            return Integer.parseInt(next());
+        }
+    }
+}
+
diff --git a/src/test/PhoneBookTest.java b/src/test/PhoneBookTest.java
new file mode 100644
index 0000000..fb898f0
--- /dev/null
+++ b/src/test/PhoneBookTest.java
@@ -0,0 +1,26 @@
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class PhoneBookTest {
+    @Test
+    void test() {
+        PhoneBook.add(911, "police");
+        PhoneBook.add(76213, "Mom");
+        PhoneBook.add(17239, "Bob");
+
+        assertEquals("Mom", PhoneBook.find(76213));
+        assertEquals("not found", PhoneBook.find(910));
+        assertEquals("police", PhoneBook.find(911));
+
+        PhoneBook.del(910);
+        PhoneBook.del(911);
+
+        assertEquals("not found", PhoneBook.find(911));
+        assertEquals("Mom", PhoneBook.find(76213));
+
+        PhoneBook.add(76213, "daddy");
+        assertEquals("daddy", PhoneBook.find(76213));
+    }
+
+}
+\ No newline at end of file