P1271 [Shenji 9. Example 1] Election of Student Union (Java & C++)

[Shenji 9. Example 1] Election of the Student Union

Topic link: https://www.luogu.com.cn/problem/P1271

Title description

The school is electing student union members. There are n(n≤999) candidates, and each candidate is numbered from 1 to n. Now m(m<=2000000) votes have been collected, and each ballot is written with a candidate serial number. Now I want to sort these piles of votes in ascending order of the number of votes cast. Enter n and m and the numbers on the m ballots to find the sorted ballot numbers.

Input format

no

Output format

no

Sample input and output

Enter #1

5 10
2 5 2 2 5 2 2 2 1 2

Output #1

1 2 2 2 2 2 2 2 5 5

Problem-solving ideas:

In C++, direct quick sorting or counting sorting can solve the problem by Jesmora, but Java direct sorting may time out or over-memory QAQ, so you can consider using StringBuffer to create string buffer objects.

code show as below:

Java

import java.util.*;

public class Main{
    
    
	public static void main(String[] args){
    
    
		Scanner sc=new Scanner(System.in);
		int[] a=new int[sc.nextInt()+1];
		int m=sc.nextInt();
		for(int i=0;i<m;i++)
			a[sc.nextInt()]++;
		StringBuffer s=new StringBuffer();  //创建字符串缓冲区对象,用于存储数据
		for(int i=1;i<a.length;i++)
			while(a[i]--!=0)
				s.append(i+" ");  //追加空格
		System.out.println(s);
	}
}

C++ (Quick Sort)

#include<iostream>
#include<algorithm>
using namespace std;
int a[2000010],n,m;
int main()
{
    
    
	cin>>n>>m;
	for(int i=0;i<m;i++)
	cin>>a[i];
	sort(a,a+m); 
	for(int i=0;i<m;i++)
	cout<<a[i]<<" ";
	return 0;
}

C++ (count sort)

#include<iostream>
using namespace std;
#define ll long long
ll b[1005],n,m,k;
int main() {
    
    
	cin>>m>>n;
	for(ll i=1; i<=n; ++i) {
    
    
		cin>>k;b[k]++;
	}
	for(ll i=1; i<=m; i++) {
    
    
		while(b[i]>0) {
    
    
			cout<<i<<" ";
			b[i]--;
		}
	}
	return 0;
}