Created
September 15, 2024 14:31
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hand write hashmap
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| class MyHashMap { | |
| static class Node { | |
| public int key; | |
| public int value; | |
| public Node prev; | |
| public Node next; | |
| } | |
| static Node first; | |
| static Node last; | |
| public MyHashMap() { | |
| } | |
| public void put(int key, int value) { | |
| Node n = new Node(); | |
| n.key = key; | |
| n.value = value; | |
| if (first == null) { | |
| first = n; | |
| last = n; | |
| } else { | |
| Node tmp = first; | |
| for (; tmp != null; tmp = tmp.next) { | |
| if (tmp.key == key) { | |
| tmp.value = value; | |
| return; | |
| } | |
| } | |
| // append to last | |
| last.next = n; | |
| // System.out.println(String.format("%v/%v/%v", first, n, last)); | |
| n.prev = last; | |
| last = n; | |
| } | |
| } | |
| public int get(int key) { | |
| if (first == null) { | |
| return -1; | |
| } | |
| Node n = first; | |
| for (; n != null; n = n.next) { | |
| // System.out.println(String.format("n %d/%d, target key is %d", n.key, n.value, | |
| // key)); | |
| if (n.key == key) { | |
| // System.out.println(String.format("found n %d/%d, target key is %d", n.key, | |
| // n.value, key)); | |
| return n.value; | |
| } | |
| } | |
| return -1; | |
| } | |
| public void remove(int key) { | |
| Node n = first; | |
| for (; n != null; n = n.next) { | |
| if (n.key == key) { | |
| n.prev.next = n.next; | |
| return; | |
| } | |
| } | |
| } | |
| } | |
| /** | |
| * Your MyHashMap object will be instantiated and called as such: | |
| * MyHashMap obj = new MyHashMap(); | |
| * obj.put(key,value); | |
| * int param_2 = obj.get(key); | |
| * obj.remove(key); | |
| */ |
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