/**

 * 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");