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Main.java

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public class Main {
    static class Entry {
        String key; int value;
        Entry next; // chain for keys sharing a bucket
        Entry(String key, int value) { this.key = key; this.value = value; }
    }

    static final int CAPACITY = 8;
    static Entry[] buckets = new Entry[CAPACITY];

    static int index(String key) { return Math.abs(key.hashCode()) % CAPACITY; }

    static void put(String key, int value) {
        int i = index(key);
        for (Entry e = buckets[i]; e != null; e = e.next) {
            if (e.key.equals(key)) { e.value = value; return; }
        }
        Entry entry = new Entry(key, value);
        entry.next = buckets[i]; // prepend to the chain
        buckets[i] = entry;
    }

    static Integer get(String key) {
        for (Entry e = buckets[index(key)]; e != null; e = e.next) {
            if (e.key.equals(key)) return e.value;
        }
        return null;
    }

    static void remove(String key) {
        int i = index(key);
        Entry prev = null;
        for (Entry e = buckets[i]; e != null; prev = e, e = e.next) {
            if (e.key.equals(key)) {
                if (prev == null) buckets[i] = e.next;
                else prev.next = e.next;
                return;
            }
        }
    }

    public static void main(String[] args) {
        put("apple", 3); put("banana", 7); put("cherry", 5);
        System.out.println("apple -> " + get("apple"));
        put("apple", 10); // update in place
        System.out.println("apple -> " + get("apple"));
        remove("banana");
        System.out.println("banana -> " + get("banana"));
    }
}