Design HashMap.

最新推荐文章于 2020-03-15 01:50:48 发布

原创最新推荐文章于 2020-03-15 01:50:48 发布 · 286 阅读

CC 4.0 BY-SA版权

本文介绍了一种使用链地址法解决冲突的哈希映射实现方式。通过定义哈希条目类LinkedHashEntry和哈希映射类HashMap，实现了基本的插入、查找和删除操作。

// use linked list for chaining.

class LinkedHashEntry {
private:
  int key;
  int value;
  LinkedHashEntry* next;

public:
  LinkedHashEntry(int key, int value) {
    this->key = key;
    this->value = value;
    this->next = NULL;
  }

  int getKey() {
    return key;
  }
  int getValue() {
    return value;
  }
  void setValue(int value) {
    this->value = value;
  }
  LinkedHashEntry* getNext() {
    return next;
  }
  void setNext(LinkedHashEntry *next){
    this->next = next;
  }
}
const int TABLE_SIZE = 128;
class HashMap {
private:
  LinkedHashEntry **table;
public:
  HashMap() {
    table  = new LinkedHashEntry*(TABLE_SIZE);
    for(int i = 0; i < TABLE_SIZE; ++i) {
      table[i] = NULL;
    }
  }

  int get(int key) {
    int hashValue = key %..
    if(table[hashValue] == NULL) {
      return -1;
    } else {
      LinkedHashEntry* entry = table(hashValue);
      while(entry != NULL && entry->getKey()  != key) {
        entry = entry->getNext();
      }
      if(entry == NULL) return -1;
      else return entry->getValue();
    }
  }
  void put(int key, int value) {
    int hashValue = key %...
    if(table[hashValue] == NULL) {
      table[hashValue] = new LinkedHashEntry(key, value);
    } else {
      LinkedHashEntry *entry = table[hashValue];
      while(entry->getNext() != NULL) {
        entry = entry->getNext();
      if(entry->getKey() == key) {entry->setValue(value);}
      else entry->setNext(new LinkedHashEntry(key, value));
    }
  }

  void remove(int key) {
    int hashValue = key % ...
    if(table[hashValue]) {
      LinkedHashEntry *prevEntry = NULL;
      LinkedHashEntry* entry = table[hashValue];
      while(entry->getNext() && entry->getKey() != key) {
        prevEntry = entry;
        entry = entry->getNext();
      }
      if(entry->getKey() == key) {
        if(prevEntry == NULL) {
          LinkedHashEntry* nextEntry = entry->getNext();
          delete entry;
          table[hash] = nextEntry;
        } else {
          LinkedHashEntry *next = entry->getNext();
          delete next;
          prevEntry->setNext(next);
        }
      }
    }
  }
  ~HashMap() {
    for(int i = 0; i < TABLE_SIZE; ++i) {
      if(table[i] != NULL) {
        LinkedHashEntry* prevEntry = NULL;
        LinkedHashEntry* entry = table[i];
        while(entry) {
          prevEntry = entry;
          entry = entry->getNext();
          delete prevEntry;
        }
      }
    }
    delete[] table;
  }
}