CCF numerical sorting (Full Score code + problem solving ideas + skill summary) 201503-2

Skill summary

For numerical pairs , An ascending order , A descending order , Use structures to store , Overloaded comparison function can be implemented （ The same is true for sorting multiple values ）

Title Description

Their thinking

• The data range is small , So we can use Count the array subscripts
• For numerical pairs , use Structure storage , Overload comparison function , Sort

Code implementation

#include <iostream>
#include <cstring>
#include <algorithm>

using namespace std;

const int N = 1010;

int a[N];

struct data
{
    
    int n;
    int c;
    
    bool operator< (const data& t) const //  Overloads the comparison function so that it is in descending order of the number of times , The values are in ascending order 
    {
    
        if(c != t.c) return c > t.c;
        else return n < t.n;
    }
}s[N];

int main()
{
    
    int n;
    cin >> n;

    int x = 0;
    for (int i = 0; i < n; i ++)
    {
    
        cin >> x;
        a[x] ++; //  Using the properties of hash table and subscript to count 
    }
    
    int cnt = 0;
    for (int i = 0; i < N; i ++) //  Notice that this is N
    {
    
        if (a[i])
        {
    
            s[cnt ++ ] = {
    i, a[i]}; //  take （ Numbers , The number of times the number appears ） Store in structure 
        }
    }
    
    sort(s, s + cnt); 
    
    for (int i = 0; i < cnt; i ++)
    {
    
        cout << s[i].n << " " << s[i].c << endl;
    }
    return 0;
}