循环有序数组查找

1.请实现以下函数int indexOf(int[] array, int target), 给定一个循环有序的数组。请在这个数组中找到指定元素，找到的话返回小标，没有找到返回-1.该数组的特点是它是一个单调递增的数组向右循环移位形成的。举例说明，原数组是[4,8,13,20,23,34,41,52]经过右循环移位后形成的数组可能是[23,34,41,52,4,8,13,20],也可能是[4,8,13,20,23,34,41,52]

实现代码一：(遍历)

import java.util.Scanner;

public class LoopArray {
    public static void main(String[] args){
        int[] array = {4,8,13,20,23,34,41,52};
        Scanner in = new Scanner(System.in);
        int num = in.nextInt();
        System.out.print("the number " + num + " is in array ?");
        System.out.println(" ");
        if(loopArrayFind(array, num) == -1){
            System.out.println("NO!");
        }else if((loopArrayFind(array, num) >= 0)&&(loopArrayFind(array, num) < array.length)){
            System.out.println("YES!");
        }else{
            System.out.println("Error!");
        }        
    }
    public static int loopArrayFind(int[] array, int num){
        int flag = 0;
        for(int i = 0; i < array.length; i++){
            if(array[i] == num){
                flag = i;
                break;
            }else
                flag = -1;
        }
        return flag;
    }
}

实现代码二：(遍历+不使用break)

import java.util.Scanner;

public class LoopArray {
    public static void main(String[] args){
        int[] array = {4,8,13,20,23,34,41,52};
        Scanner in = new Scanner(System.in);
        int num = in.nextInt();
        System.out.print("the number " + num + " is in array ?");
        System.out.println(" ");
        if(loopArrayFind(array, num) == -1){
            System.out.println("NO!");
        }else if((loopArrayFind(array, num) >= 0)&&(loopArrayFind(array, num) < array.length)){
            System.out.println("YES!");
        }else{
            System.out.println("Error!");
        }        
    }
    public static int loopArrayFind(int[] array, int num){
        int flag = -1;
        for(int i = 0; i < array.length; i++){
            if(array[i] == num){
                flag = i;
            }else;
        }
        return flag;
    }
}

实现代码三：(QuickSort)

import java.util.Scanner;

public class LoopArray {
    public static void main(String[] args){
        int[] array = {23,34,41,52,4,8,13,20};
        Scanner in = new Scanner(System.in);
        int num = in.nextInt();
        System.out.print("the number " + num + " is in array ?");
        System.out.print("  ");
        if(loopArrayFind(array, num) == -1){
            System.out.println("NO!");
        }else if((loopArrayFind(array, num) >= 0)&&(loopArrayFind(array, num) < array.length)){
            System.out.println("YES!");
        }else{
            System.out.println("Error!");
        }        
    }
    public static int loopArrayFind(int[] array, int num){
        int flag = -1;
        int low = 0;
        int high = array.length;
        int middle = (low+high)/2;
        while(middle > 0){
            if(num == array[middle]){
                flag = middle;
            }else if(num < array[middle]){
                if(num <= array[middle-1]){
                    if(num == array[middle-1]){
                        flag = middle-1;
                    }else{
                        high = middle - 1;
                    }
                }else;
            }else{
                if(middle < array.length){
                    if(num == array[middle+1]){
                        flag = middle+1;
                    }else{
                        low = middle+1;                    
                    }
                }else;
            }
            middle = (low + high)/2;
        }
        return flag;
    }
}