*6-1 CCF 2015-03-2 numerical sorting

Title Description

Source code

#include<iostream>
#include<cstring>
#include<vector>
#include<algorithm>
using namespace std;
int n;
const int N = 1005;
int rnum[N + 1];
struct number
{
    
	int num;// Numbers 
	int count;// frequency 
}num[N + 1];
bool cmp(number a, number b)
{
    
	if (a.count == b.count)
	{
    
		return a.num < b.num;  // If the count value is the same, who is the youngest and who is in the front 
	}
	return a.count > b.count;// Different count values   Who is big and who is in front 
}
int main()
{
    
	cin >> n;
	memset(num, 0, sizeof(num));
	int i, nindex;
	for (i = 1; i <= n; i++)
	{
    
		cin >> nindex;
		rnum[nindex]++;
	}
	for (int i = 1; i <= n; i++)
	{
    
		num[i].count = 0;
	}
	int ncount = 0;
	for (i = 1; i <= N; i++)// according to rnum Subscript of and the number of Statistics   initialization num Array 
	{
    
		if (rnum[i] != 0)
		{
    
			num[ncount].num = i;
			num[ncount].count = rnum[i];
			ncount++;
		}
	}
	sort(num,num+ncount,cmp);
	for (i = 0; i < ncount; i++)
	{
    
		cout << num[i].num << " " << num[i].count << endl;
	}
	return 0;
}

About this problem

The difficulty of this problem is actually that after recording How to sort
It's used here sort Sort By default, it is in ascending order Here Define a sort method for him cmp This is the key to solving the problem
sort(num,num+ncount,cmp);
bool cmp(number a, number b)
{
if (a.count == b.count)
{
return a.num < b.num; // If the count value is the same, who is the youngest and who is in the front
}
return a.count > b.count;// Different count values Who is big and who is in front
}