散列表碰撞处理、开链法、HashTable散列

散列表碰撞处理、开链法、HashTable散列

/**
 * 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");