01.quicksort.js

//quicksort
function quicksort(array){

    if(array.length <= 1) return array;
    
    var pivot = array.length % 2 == 0 ? array.length / 2 : (array.length-1)/2, 
         less = [],
         greater = [];

    for(var i = 0, len = array.length; i < len; i++){
        if(array[i] < array[pivot]){
            less.push(array[i]);
        }else if(array[i] > array[pivot]){
            greater.push(array[i]);
        }
    }

    return quicksort(less).concat(array[pivot]).concat(quicksort(greater));

}
var array = [ 12, 15, 4, 99, 2, 1, 6, 20, 21, 88 ];
console.log('quicksorting..');
console.log(array);
console.log(quicksort(array));

02.merge_sort.js

// merge sort 
function merge_sort(array){
    if (array.length <= 1) {
        return array;
    }
    var left = [],
        right = [],
        result = [],
        middle = (array.length % 2 == 0) ? array.length / 2 : (array.length-1)/2;

    for(var i = 0; i < middle; i++){
        left.push(array[i]);
    }
    for(var i = middle; i < array.length; i++){
        right.push(array[i]);
    }
   
    left = merge_sort(left);
    right = merge_sort(right);
    result = merge(left, right);
    
    return result;
        
}


function merge(p, right){
    console.log(p);
    var result = [];
    var count = 100;
    while(left.length > 0 || right.length > 0){
        if(left.length > 0 && right.length > 0){
            if(left[0] > right[0]){
                result.push(left[0]);
                left = left.splice(0,1);
                console.log(left.length);
            }else{
                result.push(right[0]);
                right = right.splice(0,1);
            }
        }else if(left.length > 0){
            result.push(left[0]);
            left = left.splice(0,1);
        }else if(right.length > 0){
            result.push(right[0]);
            right = right.splice(0,1);
        }
        count--;
        if(count == 0) return result;
    }
    return result;
}

var array = [ 12, 15, 4, 99, 2, 1, 6, 20, 21 ];
console.log('merge sorting..');
console.log(array);
console.log(merge_sort(array));

03.hash_table.js

//linked list
function List() {

    var firstNode = null;
    var lastNode = null;

    function Node(key, value) {
        this.key = key;
        this.value = value;
        this.next = null;
        this.prev = null;
        this.insertAfter = function(node){
            this.prev = node;
            this.next = node.next;
            if(node.next){
                lastNode = this;
            }else{
                node.next.prev = this;
            }
        }
    }
        
    this.add = function(key, value){
        var node = new Node(key, value);
        if(lastNode == null){
            firstNode = lastNode = node;
        }else{
            node.insertAfter(lastNode);
        }
    }
        
    this.find = function(key){
        var n = firstNode;
        while(n != null){
            if(n.key == key){
                return n.value;
            }
            n = n.next;
        }
        return null;
    }


}

//dictionary
function Dictionary() {

    var data = [];

    var hash = function(key) {
        var h = 0;
        for (var i = 0, len = key.length; i < len; i++) {
            h = 33 * h ^ key[i];
        }
        return h;
    }

    this.put = function(key, value) {
        var h = hash(key);
        if(data[h] == null){
            data[h] = new List();
        }
        data[h].add(key, value);
    }

    this.get = function(key) {
        var h = hash(key);
        if(data[h] == null){
            return null;
        }
        return data[h].find(key);
    }

}

var d = new Dictionary();
d.put("test", "lalalal");

console.log(d.get("test"));