对学生成绩进行散列

    function HashTable() {
        this.table = new Array(137);
        this.betterHash = betterHash;
        this.showDistro = showDistro;
        this.put = put;
        //this.get = get;
    }
    function simpleHash(data) {
        var total = 0;
        for ( var i = 0; i < data.length; ++i) {
            total += data.charCodeAt(i);
        }
        return total % this.table.length;
    }
    function put(data) {
        var pos = this.betterHash(data);
        this.table[pos] = data;
    }
    function betterHash(data) {
        var cons = 31;//此参数的设置是为了避免碰撞
        var total = 0;
        for ( var i = 0; i < data.length; ++i) {
            total += cons * total + data.charCodeAt(i);
        }
        total = total % this.table.length;
        document.write("Hash value: " + data + " -> " + total + "<br />");//测试是否有相同的散列值
        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] != undefined) {
                document.write(i + ": " + this.table[i]);
                document.write("<br />");
            }
        }
    }
    function getRandomInt(min, max) {//此方法随机获得50-100之间的学生成绩值
        return Math.floor(Math.random() * (max - min + 1)) + min;
    }
    function genStuData(arr) {
        for ( var i = 0; i < arr.length; ++i) {
            var num = "";
            for ( var j = 1; j <= 9; ++j) {//此循环随机获得学生成绩的ID值
                num += Math.floor(Math.random() * 10);//注意num是个字符串
            }
            num += getRandomInt(50, 100);//将随机获得的ID值与学生成绩相连接
            arr[i] = num;
        }
    }
    var numStudents = 10;//数组中的数据长度
    var students = new Array(numStudents);
    genStuData(students);
    document.write("Student data: <br />");
    for ( var i = 0; i < students.length; ++i) {
        document.write(students[i].substring(0, 8) + " "
                + students[i].substring(9) + "<br />");
    }
    document.write("Data distribution: <br />");
    var hTable = new HashTable();
    for ( var i = 0; i < students.length; ++i) {
        hTable.put(students[i]);
    }
    hTable.showDistro();