Complete diagram / Euler loop

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Complete graph ： A complete graph is a simple undirected graph , Each edge has a different pair of vertices . Complete graphs have at most n*(n-1)/2 side

Find the minimum and maximum of the longest path ：
minimum value ： First, the longest path cannot have a ring , Otherwise it will be infinite , So in the acyclic case , Every point goes through once , The minimum value of the longest path is $n-1$
Maximum ： Go all the way —— Euler circuit , And because the Euler circuit of an undirected graph has at most $(n-1)n/2$ side , The Euler loop requires that the points of odd degree of an undirected graph have at most 2 individual , Discussion on odd and even points

1. Odd points ：$n$ It's odd ,$(n-1)$ For the even , therefore $n$ An odd number of points. Each point has $(n-1)$ Even edges , Conform to Euler circuit , The length is $(n-1)n/2$
2. Even points ： even numbers $n$ One point is $(n-1)$ Odd edges , Because there are at most two odd sides , So there is $(n-2)$ A dot needs to delete an edge , Because an undirected graph , So a total of $(n-2)/2$ side , The length is $(n-1)n/2-(n-2)/2$

#include<iostream>
using namespace std;

int main()
{
    
    long long n;
    cin>>n;
    
    if(n&1) cout<<n-1<<" "<<(n-1)*n/2<<endl;
    else cout<<n-1<<" "<<(n-1)*n/2-(n-2)/2<<endl;
    
    return 0;
}