127 lines
2.8 KiB
Dart
127 lines
2.8 KiB
Dart
/**
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* File: array_hash_map.dart
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* Created Time: 2023-03-29
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* Author: liuyuxin (gvenusleo@gmail.com)
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*/
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/* Key-value pair */
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class Pair {
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int key;
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String val;
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Pair(this.key, this.val);
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}
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/* Hash table based on array implementation */
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class ArrayHashMap {
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late List<Pair?> _buckets;
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ArrayHashMap() {
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// Initialize an array, containing 100 buckets
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_buckets = List.filled(100, null);
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}
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/* Hash function */
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int _hashFunc(int key) {
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final int index = key % 100;
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return index;
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}
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/* Query operation */
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String? get(int key) {
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final int index = _hashFunc(key);
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final Pair? pair = _buckets[index];
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if (pair == null) {
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return null;
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}
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return pair.val;
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}
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/* Add operation */
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void put(int key, String val) {
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final Pair pair = Pair(key, val);
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final int index = _hashFunc(key);
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_buckets[index] = pair;
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}
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/* Remove operation */
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void remove(int key) {
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final int index = _hashFunc(key);
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_buckets[index] = null;
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}
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/* Get all key-value pairs */
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List<Pair> pairSet() {
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List<Pair> pairSet = [];
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for (final Pair? pair in _buckets) {
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if (pair != null) {
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pairSet.add(pair);
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}
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}
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return pairSet;
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}
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/* Get all keys */
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List<int> keySet() {
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List<int> keySet = [];
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for (final Pair? pair in _buckets) {
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if (pair != null) {
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keySet.add(pair.key);
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}
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}
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return keySet;
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}
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/* Get all values */
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List<String> values() {
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List<String> valueSet = [];
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for (final Pair? pair in _buckets) {
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if (pair != null) {
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valueSet.add(pair.val);
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}
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}
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return valueSet;
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}
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/* Print hash table */
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void printHashMap() {
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for (final Pair kv in pairSet()) {
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print("${kv.key} -> ${kv.val}");
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}
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}
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}
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/* Driver Code */
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void main() {
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/* Initialize hash table */
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final ArrayHashMap map = ArrayHashMap();
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/* Add operation */
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// Add key-value pair (key, value) to the hash table
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map.put(12836, "Ha");
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map.put(15937, "Luo");
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map.put(16750, "Suan");
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map.put(13276, "Fa");
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map.put(10583, "Ya");
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print("\nAfter adding, the hash table is\nKey -> Value");
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map.printHashMap();
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/* Query operation */
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// Enter key to the hash table, get value
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String? name = map.get(15937);
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print("\nInput student ID 15937, found name $name");
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/* Remove operation */
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// Remove key-value pair (key, value) from the hash table
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map.remove(10583);
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print("\nAfter removing 10583, the hash table is\nKey -> Value");
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map.printHashMap();
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/* Traverse hash table */
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print("\nTraverse key-value pairs Key->Value");
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map.pairSet().forEach((kv) => print("${kv.key} -> ${kv.val}"));
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print("\nIndividually traverse keys Key");
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map.keySet().forEach((key) => print("$key"));
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print("\nIndividually traverse values Value");
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map.values().forEach((val) => print("$val"));
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}
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