Baidu written test 2022.4.12 + programming topic: simple integer problem

package demo;

import java.util.*;

public class Main1 {
    
    public static void main(String[] args) {
    
        //List<Integer> list=new ArrayList<>(Arrays.asList(1,2,1,3,5,4,2,1,3,3));
        // Input 
        Scanner cin=new Scanner(System.in);
        int size=cin.nextInt();
        cin.nextLine();
        String string=cin.nextLine();
        String[] arrstring= string.split(" ");
        List<Integer> list=new ArrayList<>();
        for(int i=0;i<arrstring.length;i++){
    
           list.add(Integer.parseInt(arrstring[i])) ;
        }
        System.out.println(list);

        // Store a set of data in a map Go to the assembly .
        Map<Integer,Integer> map = new TreeMap();
        for(int i=0;i<list.size();i++){
    
            Integer count=1;
            if(map.containsKey(list.get(i))){
    
                count=map.get(list.get(i));
                count++;
            }
            map.put(list.get(i),count); // Will automatically overwrite 
        }
        // Put the set into the array （ Traverse ）
        int[][] data=new int[map.size()][2];
        int i=0;
        for (Map.Entry<Integer,Integer> entry : map.entrySet()) {
    
            data[i][0] =entry.getKey();
            data[i++][1] =entry.getValue();
        }

        // Sort the array 
        int m=0;
        int n=0;
        int result=0;
        // Sort by the second column from large to small ,
        Arrays.sort(data,(a,b)->{
    
            if(a[1]==b[1]) return b[0]-a[0];
            return b[1]-a[1];
        });
        System.out.println(Arrays.deepToString(data));
        m=data[0][0];
        Arrays.sort(data,(a,b)->{
    
            if(a[1]==b[1]) return a[0]-b[0];
            return a[1]-b[1];
        });
        System.out.println(Arrays.deepToString(data));
        n=data[0][0];
        result=m-n;
        System.out.println("result="+result);
        }
}

// Sum up your thoughts
1）Map Set up
2）Map Traversal of the set

package demo;

import java.util.*;

public class main3 {
    
    public static void main(String[] args) {
    
        // Change two sets of numbers into map aggregate 
        List<String> name=new ArrayList<>(Arrays.asList("a","b","c","d"));
        List<Integer> age=new ArrayList<>(Arrays.asList(1,2,3,4));
        Map<String,Integer> map=new TreeMap<>();
        for(int i=0;i<name.size();i++){
    
            map.put(name.get(i),age.get(i));
        }
        System.out.println(map);

        // Count the number of elements in an array , And into map aggregate 
        List<Integer> data=new ArrayList<>(Arrays.asList(1,2,3,3,2,1,2,3,4,5,6,6,5,4,3));
        Map<Integer,Integer> map1=new TreeMap<>();

        for(int i=0;i<data.size();i++){
    
            Integer count=1;
            if(map1.containsKey(data.get(i))){
    
                count=map1.get(data.get(i));
                count++;
            }
            map1.put(data.get(i),count);
        }
        System.out.println(map1);


        // The way to traverse 
        for(Map.Entry<String,Integer> entry: map.entrySet()){
    
            String string=entry.getKey();
            Integer integer=entry.getValue();
            System.out.println("string="+string+" "+"integer="+integer);
        }

    }
}