2021-01-25

自主数据库模型
排序：package com.huawei;

public class Main {

public static void main(String[] args) {
    int[] a = new int[10];
    a = new int[]{12, 21, 34, 32, 2, 12, 56, 31, 98, 65, 46};
    int[] b = new int[10];
    int len = a.length;
    for (int i = 0; i < len - 1; i++) {
        for (int j = 0; j < len - 1 - i; j++) {
            if (a[j] > a[j + 1]) {        // 相邻元素两两对比
                int temp = a[j + 1];        // 元素交换
                a[j + 1] = a[j];
                a[j] = temp;
            }
        }
    }
    for (int i = 0; i < a.length; i++) {
        System.out.print(a[i]+" ");

    }
}

}
去重：package com.huawei;
import java.util.Random;
import java.util.Scanner;
import java.util.stream.IntStream;

public class Main {

public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int[] ran1 = new int[N];
    for (int i = 0; i < N; i++) {
        ran1[i] = sc.nextInt();
    }
    for (int m = 1; m < N; m++) {
        for (int n = N - m; n < N; n++) {
            if (ran1[n - 1] > ran1[n]) {
                int temp = ran1[n - 1];
                ran1[n - 1] = ran1[n];
                ran1[n] = temp;
            }
        }
    }
    int count[] = new int[62];
    int count12[][] = new int[62][62];
    String chen = "";
    for (int m = 0; m < 62; m++) {
        count[m] = 0;
    }
    for (int i = 0; i < ran1.length-1; i++) {
        if (ran1[i] == ran1[i+1])
            for (int j = i; j < ran1.length-1; j++) {
                ran1[j] = ran1[j+1];
            }
    }
    for (int i = 0; i < N-3; i++) {
        System.out.println(ran1[i]);
    }
}

}
查找：
import java.util.Arrays;
import java.util.Random;
import java.util.stream.Stream;

import static java.lang.String.format;

public class IterativeBinarySearch {
/**
* This method implements an iterative version of binary search algorithm
*
* @param array a sorted array
* @param key the key to search in array
* @return the index of key in the array or -1 if not found
*/
public int find(T[] array, T key) {
int l, r, k, cmp;

    l = 0;
    r = array.length - 1;

    while (l <= r) {
        k = (l + r) / 2;
        cmp = key.compareTo(array[k]);

        if (cmp == 0) {
            return k;
        } else if (cmp < 0) {
            r = --k;
        } else {
            l = ++k;
        }
    }

    return -1;
}

//Only a main method for test purpose
public static void main(String[] args) {
    Random r = new Random();
    int size = 100;
    int maxElement = 100000;
    Integer[] integers = Stream.generate(() -> r.nextInt(maxElement)).limit(size).sorted().toArray(Integer[]::new);


    //the element that should be found
    Integer shouldBeFound = integers[r.nextInt(size - 1)];

    IterativeBinarySearch search = new IterativeBinarySearch();
    int atIndex = search.find(integers, shouldBeFound);

    System.out.println(String.format("Should be found: %d. Found %d at index %d. An array length %d"
            , shouldBeFound, integers[atIndex], atIndex, size));


    int toCheck = Arrays.binarySearch(integers, shouldBeFound);
    System.out.println(format("Found by system method at an index: %d. Is equal: %b", toCheck, toCheck == atIndex));
}

}