Game Map------Gym

#include<bits/stdc++.h>

using namespace std;

vector<int> ve[1000005];
int a[1000005];

struct node
{
    int id;
    int num;
    int jieguo;
}s[1000005];

bool cmp(node a, node b)
{
    return a.num < b.num;
}

int main()
{
    int n, m, pos, u, v, maxx;
    int anss;

    scanf("%d %d", &n, &m);
    for(int i=0;i<n;i++)
    {
        s[i].id = i;
    }

    while(m--)
    {
        scanf("%d %d", &u, &v);
        s[u].num++;
        s[v].num++;
        ve[u].push_back(v);
        ve[v].push_back(u);
    }

    sort(s, s+n, cmp);
    for(int i=0;i<n;i++)
    {
        a[s[i].id] = i;
    }

    anss = 1;
    for(int i=0;i<n;i++)
    {
        maxx = 1;
        for(auto it:ve[s[i].id])
        {
            pos = it;
            if(s[a[pos]].num < s[i].num)
                maxx = max(s[a[pos]].jieguo + 1, maxx);
        }
        s[i].jieguo = maxx;
        anss = max(anss, s[i].jieguo);
    }

    printf("%d
", anss);
    return 0;
}