JS散列表碰撞处理、开链法、HashTable散列示例_JavaScript

JS散列表碰撞处理、开链法、HashTable散列示例

本文实例讲述了js散列表碰撞处理、开链法、hashtable散列。分享给大家供大家参考，具体如下：

/**
 * 散列表碰撞处理、开链法、hashtable散列。
 * 将数组里的元素位置，也设置为数组，当两个数据的散列在同一个位置时，
 * 就可以放在这个位置的二维数组里，解决了散列函数的碰撞处理问题
 */
function hashtable() {
  this.table = new array(137);
  this.betterhash = betterhash;//散列函数
  this.showdistro = showdistro;//显示散列表里的数据
  this.buildchains = buildchains;//生成二维数组
  this.put = put;//将数据存储到散列表
  this.get = get;//从散列表中取出某个数据
}
// put for separate chaining
function put(key, data) {
  var pos = this.betterhash(key);
  var index = 0;
  if (this.table[pos][index] == undefined) {
    this.table[pos][index] = data;
  }else {
    while (this.table[pos][index] != undefined) {
      ++index;
    }
    this.table[pos][index] = data;
  }
}
/*散列函数*/
function betterhash(string) {
  const h = 37;
  var total = 0;
  for (var i = 0; i < string.length; ++i) {
    total += h * total + string.charcodeat(i);
  }
  total = total % this.table.length;
  if (total < 0) {
    total += this.table.length-1;
  }
  return parseint(total);
}
function showdistro() {
  var n = 0;
  for (var i = 0; i < this.table.length; ++i) {
    if (this.table[i][n] != undefined) {
      console.log(i + ": " + this.table[i]);
    }
  }
}
function buildchains() {
  for (var i = 0; i < this.table.length; ++i) {
    this.table[i] = new array();
  }
}
// get for separate chaining
function get(key) {
  var index = 0;
  var pos = this.betterhash(key);
  while ((this.table[pos][index] != undefined)&&(this.table[pos][index] != key)) {
    index += 1;
  }
  if(this.table[pos][index] == key) {
    console.log(key+" 的键值为： "+this.table[pos][index]);
    return this.table[pos][index];
  }else{
    console.log("无该键值");
    return undefined;
  }
}
/*测试开链法*/
var somenames = ["david", "jennifer", "donnie", "raymond",
  "cynthia", "mike", "clayton", "danny", "jonathan"];
var htable = new hashtable();
htable.buildchains();
for (var i = 0; i < somenames.length; ++i) {
  htable.put(somenames[i],somenames[i]);
}
htable.showdistro();
htable.betterhash("jennifer");
htable.get("jennidfer");
htable.get("jennifer");

使用在线html/css/javascript代码运行工具：测试上述代码，可得如下运行结果：