二分查找：

---缺点是必须为有序，如果是无序，可先排序---

package com.wjb.demo;
/**
 * Created by wjb on 2017/5/10.
 */
public class SocketDemo {
    public int binarySearch(int[] array,int key){
        int left = 0;
        int right = array.length-1;
        while(left <= right){
            int mid = (left + right) / 2;
            if(array[mid] == key){
                return mid;
            }else if(array[mid] < key){
                left = mid + 1;
            }else{
                right = mid - 1;
            }
        }
        return -1;
    }
    public static void main(String[] args) {
        int i = new SocketDemo().binarySearch(new int[]{1,2,3,4,5},1);
        System.out.println(i);
    }
}

直接插入排序：

package com.wjb.demo;

/**
 * Created by wjb on 2017/5/10.
 */
public class SocketDemo {
    public void insertSort(int[] a) {
        for (int i = 1; i < a.length; i++) {
            if (a[i] < a[i - 1]) {
                int j;
                int x = a[i];     //x为待插入元素
                a[i] = a[i - 1];
                for (j = i - 1; j >= 0 && x < a[j]; j--) {   //通过循环，逐个后移一位找到要插入的位置。
                    a[j + 1] = a[j];
                }
                a[j + 1] = x;     //插入
            }
        }
    }
    public static void main(String[] args) {
        int[] array = {1, 3, 2, 0, 5, 20, 10};
        new SocketDemo().insertSort(array);
        for(int i : array){
            System.out.println(i);
        }
    }
}

冒泡排序：

---升序---

package com.wjb.demo;

/**
 * Created by wjb on 2017/5/10.
 */
public class SocketDemo {
    public void BubbleSort(int[] array) {
        for(int i = 0;i < array.length;i++){
            for(int j = 0;j < array.length - i - 1;j++){
                if(array[j] > array[j+1]){
                    int temp = array[j];
                    array[j]=array[j+1];
                    array[j+1]=temp;
                }
            }
        }
    }
    public static void main(String[] args) {
        int[] array = {1, 3, 2, 0, 5, 20, 10};
        new SocketDemo().BubbleSort(array);
        for(int i:array){
            System.out.println(i);
        }
    }
}

裴波那契函数：

package demo;

import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

/**
 * Created by wjb on 2016/12/20.
 */
//    f(0)=1;     f(1)=2;
//    f(n)=f(n-1)+f(n-2);
    
public class Test2 {
    public static void main(String[] args) {
        Date date =  new Date();
        long time1 = date.getTime();
        SimpleDateFormat sd = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
        System.out.println("当前时间是：" + sd.format(date));
        System.out.println(f2(10));
        Date date2  = new Date();
        long time = date2.getTime();
        System.out.print("执行花了："+(time-time1)+"毫秒");

    }

    public static int f(int n) {
        if(n == 1 || n == 2) {
            return n;
        } else {
            return f(n - 1) +f(n - 2);
        }

    }

    
    public static long f2(int n){
        List<Integer> list = new ArrayList<Integer>();
        list.add(1);
        list.add(2);
        for(int i =2;i<n;i++){
            list.add(list.get(i-1)+list.get(i-2));
        }
        return list.get(n-1);
    }

    /* 速度最快的方法 */
    public static long f3(int n){
        Integer[] arr = new Integer[2];
        arr[0]=1;
        arr[1]=2;
        for (int i = 2; i< n; i++){
            arr[i%2] = arr[0] + arr[1];
        }
        return arr[(n-1)%2];
    }
}