算法及其相关

算法基础

队列：先进先出，后进后出

public class dui {
    private Object[] objects;
    private int size;
    private int head;
    private int end;

    public dui(int size){
        this.objects = new Object[size];
        this.head = 0;
        this.end = 0;
        this.size = 0;
    }   
    public void push(Object object) throws Exception{
        if(this.size>objects.length)
            throw new Exception("Queue is full");
        objects[end++] = object;
        size++;
    }   
    public Object pop()throws Exception{
        if(this.size == 0) 
        //  return null;
           throw new Exception("Queue is empty!");  
           if(head == objects.length)
                this.head = 0;
            size--;
            return objects[head++];
    }   
    public Object peek() throws Exception{
        if(this.size == 0)
            throw new Exception("Queue is empty!");
        return objects[head];       
    }
}

栈：先进后出，后进先出

public class Stack {
    private Object[] objects;
    private int head;
    private int size;

    public Stack (int size){
        objects = new Object[size];
        this.head = 0;
        this.size = 0;
    }

    public void push(Object object) throws Exception{
        if (this.size == objects.length)
            throw new Exception("this stack is full");
        objects[head++] = object;
        size++;
    }

    public Object pop() throws Exception{
        if (size == 0)
            throw new Exception("this stack is empty");
        size--;

        return objects[--head];
    }
}

斐波那契数列两种实现:递归和非递归

//递归方法
public class feibo {
    private static int getFibo(int i){
        if (i==1) return 1;
        if (i==2) return 1;


        else 
            return getFibo(i-1)+getFibo(i-2);
    }
    public static void main(String[] args){
        for(int j=1;j<=20;j++){
            System.out.print(getFibo(j)+"\t");
            if(j % 5 == 0)
                System.out.println();
        }
    }
}

冒泡排序

public class mao {
    public static void main(String[] args) {
        int[] f={3,5,7,12,9,13,14};
        int a;
        for(int i=0;i<f.length;i++){
            for(int j=0;j<f.length-i-1;j++){
                if(f[j]<f[j+1])
                {
                    a=f[j];
                    f[j]=f[j+1];
                    f[j+1]=a;
                }           
            }           
        }
        System.out.print("最终循环结果" + " ");
        for (int i : f) {
            System.out.print(i + " ");
        }       
    }
}

快速排序

public class Array {
    public static int partition(int []array,int lo,int hi){

        int key=array[lo];
        while(lo<hi){
            while(array[lo]<=key&&hi>lo){//从前边找大的
                lo++;
             }//
            array[hi]=array[lo];

            while(array[hi]>=key&&hi>lo){//从后边找小的
                hi--;
            }
            array[lo]=array[hi];            
        }
        array[hi]=key;
       return hi;       
    }

    public static void sort(int []array,int lo,int hi){
        if(lo>=hi){
            return;
        }
        int index =partition(array,lo,hi);
        sort(array,lo,index-1);
        sort(array,index+1,hi);     
    }
    public static void main(String[] args) {
        int []array={49,27,97,76,13,65,38};
        sort(array,0,array.length-1);
        for(int i:array){
            System.out.print(i+" ");
        }
    }    
}