刷题记录（2）

1. HWOD机试 - 模拟消息队列(100)

package com.yue.test;

import org.junit.Test;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;

/**
 * @Author: 夜雨
 * @Date: 2021-12-08-10:31
 * @Description:
 * @Version 1.0
 */
public class tsest01 {
    @Test
    public void demo01() {
        String one = "2 22 1 11 4 44 5 55 3 33";
        String two = "1 7 2 3";
        LinkedList<String> baseOne = new LinkedList<>(Arrays.asList(one.split(" ")));
        LinkedList<String> baseTwo = new LinkedList<>(Arrays.asList(two.split(" ")));
        int resultSize = baseTwo.size() / 2;
        List<List<Integer>> result = new ArrayList<>();
        for (int j = baseTwo.size() - 1; j >= 0; j -= 2) {
            List<Integer> tmp = new ArrayList<>();
            for (int k = 0; k < baseOne.size() - 1; ) {
                int time = Integer.parseInt(baseOne.get(k));
                if (Integer.parseInt(baseTwo.get(j)) > time && Integer.parseInt(baseTwo.get(j - 1)) <= time) {
                    tmp.add(Integer.valueOf(baseOne.get(k + 1)));
                    baseOne.remove(k);
                    baseOne.remove(k);
                    continue;
                }
                k += 2;
            }
            if (tmp.isEmpty()){
                tmp.add(-1);
            }
            result.add(tmp);
        }
        
    }


}

改进

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        String[] aStr = scanner.nextLine().split(" ");
        int[] a = new int[aStr.length];
        for (int i = 0; i < aStr.length; i++) {
            a[i] = Integer.parseInt(aStr[i]);
        }

        List<Pair> t = new ArrayList<>();
        for (int i = 0; i < a.length; i += 2) { // 第一行输入两个一对，为发布者的发布时刻和发布内容
            t.add(new Pair(a[i], a[i + 1]));
        }
        t.sort(null); // 按发布时间排序

        String[] bStr = scanner.nextLine().split(" ");
        int[] b = new int[bStr.length];
        for (int i = 0; i < bStr.length; i++) {
            b[i] = Integer.parseInt(bStr[i]);
        }

        List<List<Integer>> msg = new ArrayList<>();
        for (int i = 0; i < b.length - 1; i += 2) {
            msg.add(new ArrayList<>());
        }

        for (Pair pair : t) {
            int x = pair.x;
            int y = pair.y;
            int ans = -1;
            for (int i = b.length - 2; i >= 0; i -= 2) { // 从优先级高的订阅者开始遍历，优先匹配优先级高的订阅者
                if (b[i] <= x && x < b[i + 1]) { // 如果发布时刻在订阅时间中，订阅者收到发布内容
                    ans = i / 2;
                    break; // 只有优先级最高的收到
                }
            }
            if (ans != -1) {
                msg.get(ans).add(y); // 收到内容
            }
        }

        for (List<Integer> list : msg) {
            if (list.isEmpty()) {
                System.out.println(-1);
            } else {
                for (int i : list) {
                    System.out.print(i + " ");
                }
                System.out.println();
            }
        }
    }

    static class Pair implements Comparable<Pair> {
        int x, y;

        public Pair(int x, int y) {
            this.x = x;
            this.y = y;
        }

        @Override
        public int compareTo(Pair other) {
            return Integer.compare(this.x, other.x);
        }
    }
}

2. 分割数组的最大差值(100)

import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int n = scanner.nextInt();
        int[] nums = new int[n];
        long sum = 0;

        for (int i = 0; i < n; i++) {
            int num = scanner.nextInt();
            sum += num;
            nums[i] = num;
        }

        long maxAbs = 0, leftSum = 0;
        for (int i = 0; i < n - 1; i++) {
            leftSum += nums[i];

            // rightSum = sum - leftSum, 差值 = rightSum - leftSum = Math.abs(sum - leftSum)
            maxAbs = Math.max(maxAbs, Math.abs(sum - 2 * leftSum));
        }

        System.out.println(maxAbs);
    }
}

3. 数值同化(200)-BFS

存在一个m*n的二维数组，其成员取值范围为0,1,2。其中值为1的元素具备同化特性，每经过1s,将上下左右值为0的元素同化为1。而值为2的元素，免疫同化。将数组所有成员随机初始化为0或2，再将矩阵的[0,0]元素修改成1，在经过足够长的时间后，求矩阵中有多少个元素是0或2（即0和2数量之和）

输入：输入的前两个数字是矩阵大小。后面的数字是矩阵内容。

如：4 4

\[0, 0, 0, 0\], \[0, 2, 2, 2\], \[0, 2, 0, 0\], \[0, 2, 0, 0\]

输出：返回矩阵中非1的元素个数

import java.util.*;  
  
public class MatrixAssimilation {  
  
    static class Point {  
        int x, y;  
  
        Point(int x, int y) {  
            this.x = x;  
            this.y = y;  
        }  
    }  
  
    public static int countNonOnes(int[][] matrix) {  
        int m = matrix.length;  
        int n = matrix[0].length;  
  
        // 使用队列来进行BFS  
        Queue<Point> queue = new LinkedList<>();  
  
        // 初始化，将所有初始值为1的点加入队列  
        for (int i = 0; i < m; i++) {  
            for (int j = 0; j < n; j++) {  
                if (matrix[i][j] == 1) {  
                    queue.offer(new Point(i, j));  
                }  
            }  
        }  
  
        // 定义四个方向的偏移量  
        int[][] directions = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}};  
  
        // 广度优先搜索  
        while (!queue.isEmpty()) {  
            Point current = queue.poll();  
            for (int[] dir : directions) {  
                int newX = current.x + dir[0];  
                int newY = current.y + dir[1];  
                // 检查新坐标是否有效且值为0  
                if (newX >= 0 && newX < m && newY >= 0 && newY < n && matrix[newX][newY] == 0) {  
                    // 同化该点，并将其加入队列以便进一步同化其相邻的0  
                    matrix[newX][newY] = 1;  
                    queue.offer(new Point(newX, newY));  
                }  
            }  
        }  
  
        // 计算非1的元素个数  
        int count = 0;  
        for (int i = 0; i < m; i++) {  
            for (int j = 0; j < n; j++) {  
                if (matrix[i][j] != 1) {  
                    count++;  
                }  
            }  
        }  
  
        return count;  
    }  
  
    public static void main(String[] args) {  
        Scanner scanner = new Scanner(System.in);  
        int m = scanner.nextInt();  
        int n = scanner.nextInt();  
        int[][] matrix = new int[m][n];  
  
        for (int i = 0; i < m; i++) {  
            for (int j = 0; j < n; j++) {  
                matrix[i][j] = scanner.nextInt();  
            }  
        }  
  
        // 确保起始点为1  
        if (matrix[0][0] != 1) {  
            matrix[0][0] = 1;  
        }  
  
        System.out.println(countNonOnes(matrix));  
    }  
}

4. 数组组成的最小数字(100)

public class Test {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String[] str = scanner.nextLine().split(",");
        Arrays.sort(str, (a, b) -> {
            int lengthA = a.length();
            int lengthB = b.length();
            if (lengthA != lengthB) {
                return lengthA - lengthB;
            } else {
                return a.compareTo(b);
            }
        });

        StringBuilder stringBuilder = new StringBuilder();
        if (str.length == 1) {
            stringBuilder.append(str[0]);
            System.out.println(stringBuilder);
        } else if (str.length == 2) {
            String s1 = str[0] + str[1];
            String s2 = str[1] + str[0];
            stringBuilder.append(s1.compareTo(s2) < 0 ? s1 : s2);
            System.out.println(stringBuilder);
        } else {
            String[] res = Arrays.copyOf(str, 3);
            Arrays.sort(res);
            for (String r : res) {
                System.out.print(r);
            }
        }
    }
}

5. 垃圾信息拦截(200)

问题描述：按照如下规则进行垃圾信息识别，发送者A符合以下条件之一，则认为A为垃圾信息发送者：

A发送短信的接收者中，没有发过短信给A的人数L＞5

A发送的短信数-A接收的短信数M＞10

如果存在X，A发送给X的短信数-A接收到X的短信数N＞5

输入描述第一行为条目数目，接下来几行是具体的条目，每个条目是一对ID，第一个数字是发送者ID，后面的数字是接收者ID，中间空格隔开，所有的ID都是为无符号整型，ID最大值为100；

同一个条目中，两个ID不会相同（不会自己给自己发信息）

最后一行为指定ID

输出描述：输出该ID是否为垃圾短信发送者，并且按序列输出L M的值（由于N值不唯一，不需要输出）

例：输入：

15
1 2
1 3
1 4
1 5
1 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
14 1
1 15
1

输出：

true 13 13

输入：

15
1 2
1 3
1 4
1 5
1 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
14 1
1 15
2

输出：

false 0 -1

public class Test {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        List<Msg> msgList = new ArrayList<>();
        int count = Integer.parseInt(scanner.nextLine());
        for (int i=0;i<count;i++){
            String[] str = scanner.nextLine().split(" ");
            msgList.add(new Msg(Integer.parseInt(str[0]),Integer.parseInt(str[1])));
        }
        Boolean flag = false;
        int A = Integer.parseInt(scanner.nextLine());

        List<Msg> aSendList = msgList.stream().filter(msg -> msg.sendUser==A).collect(Collectors.toList());
        List<Integer> receiveFromA = aSendList.stream().map(msg -> {return msg.receiveUser;}).distinct().collect(Collectors.toList());

        List<Msg> otherSendList = msgList.stream().filter(msg -> msg.sendUser!=A).collect(Collectors.toList());

        List<Integer> aReceiveList = msgList.stream().filter(msg -> msg.receiveUser==A).map(msg -> {return msg.sendUser;}).collect(Collectors.toList());


        int M = aSendList.size()-aReceiveList.size();
        int L = aSendList.size();
        for (int i=0;i<otherSendList.size();i++){
            if (receiveFromA.contains(otherSendList.get(i).sendUser)){
                L-=1;
            }
        }

        if (M>10 || L>5){
            flag = true;
            System.out.print(flag + " " +   L + " " + M);
        }else {

            List<Msg> msgList1 = new ArrayList<>();
            for (int i = 0;i<receiveFromA.size();i++) {
                int Y = 0;
                int X = 0;
                int id = receiveFromA.get(i);

                Y = aReceiveList.stream().filter(m -> id ==m).collect(Collectors.toList()).size();
                X = aSendList.stream().filter(msg -> msg.receiveUser == id).collect(Collectors.toList()).size();
                if (Math.abs(X-Y)>5){
                    flag = true;
                    break;
                }

            }

            System.out.print(flag + " " +   L + " " + M);
        }

    }
    static  class  Msg{
        int sendUser;
        int receiveUser;
        Msg( int sendUser, int receiveUser){
            this.sendUser = sendUser;
            this.receiveUser = receiveUser;
        }

    }
}