Java小练习 数组的复制，反转及查找（线性，二分）

Posted 2021-03-14 Goldexperience

/*
    算法:
    数组的复制，反转，查找（线性查找，二分查找）
*/

import java.util.Scanner;

public class arrayCopyReverseSearch {
    public static void main(String[] args) {
        String[] arr = new String[]{"AA", "BB", "CC", "DD", "EE", "FF"};
        //数组的复制
        String[] arr1 = new String[arr.length];
        for (int i = 0; i < arr.length; i++) {
            arr1[i] = arr[i];
            System.out.print(arr1[i]);
        }
        System.out.println();
        System.out.println("--------------------------");
        //数组的反转
        for (int i = 0; i < arr.length / 2; i++) {
            String temp = arr[i];
            arr[i] = arr[arr.length - 1 - i];
            arr[arr.length - 1 - i] = temp;
        }
        //遍历
        for (int i = 0; i < arr.length; i++) {
            System.out.print(arr[i]);
        }
        System.out.println();
        System.out.println("--------------------------");
        //查找
        //1,线性查找
        boolean isSearched1 = false;
        System.out.println("请输入arr1中要查找的元素");
        Scanner scan = new Scanner(System.in);//输入要查找的元素
        String dest1 = scan.next();
        for (int i = 0; i < arr1.length; i++) {
            if (dest1.equals(arr1[i])) {//即dest=arr1[i]
                System.out.println("查找成功，" + dest1 + "位于数组arr1第" + (i + 1) + "个");
                isSearched1 = true;
                break;
            }
        }
        if (!isSearched1) {
            System.out.println("很抱歉没有找到");
        }
        //2,二分法查找
        //前提：查找的序列必须有序
        int[] arr2 = new int[]{-51, -31, -25, -10, 1, 17, 31, 48, 79, 97};
        System.out.println("请输入arr2中要查找的元素");
        int dest2 = scan.nextInt();
        //设置首尾"指针"
        int head = 0;
        int end = arr2.length-1;
        boolean isSearched2 = false;
        while (head <= end) {
            int mid = (head + end) / 2;
            if (dest2 == arr2[mid]) {
                System.out.println("查找成功，" + dest2 + "位于数组arr2第" + mid + "个");
                isSearched2 = true;
                break;
            } else if (dest2 < arr2[mid]) {
                end = mid - 1;//若目标数<"中位数",则调整尾指针
            } else {
                head = mid + 1;//若目标数>"中位数",则调整头指针
            }
        }
        if (!isSearched2) {
            System.out.println("很抱歉没有找到");
        }
    }
}