Submission #1268734

#	Time	Username	Problem	Language	Result	Execution time	Memory
1268734		ilovewaguri	Cijanobakterije (COCI21_cijanobakterije)	C++20	70 / 70	26 ms	12100 KiB

Main

#include<bits/stdc++.h>
using namespace std;
#define NAME "CHAIN"
#define nl '\n'
#define allofa(x,sz) x,x+sz+1
#define allof(x) x.begin(),x.end()
#define allof1(x) x.begin()+1,x.end()
#define mset(x,val) memset(x,val,sizeof(x))
#define couf(x) cout << fixed << setprecision(x)
template<class T> T Abs(T &x) {return (x>=0 ? x : -x);};
template<class X,class Y> bool minimize(X &a, Y b){if(a>b) {a=b;return true;}return false;};
template<class X,class Y> bool maximize(X &a, Y b){if(a<b) {a=b;return true;}return false;};
typedef long long ll;
const ll mod = (long long)1e9+7;
const ll LINF = (long long)1e15;
const int INF = (int)1e9;
const int MAXN = (int)1e5+5;
vector<int> graph[MAXN];
bool visited[MAXN];
int n,m;

void ccps() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);
    if(fopen(NAME".inp","r")) {
        freopen(NAME".inp","r",stdin);
        freopen(NAME".out","w",stdout);
    }
}

pair<int,int> dfs(int u, int pre) {
    visited[u] = true;
    pair<int,int> ret(u,1);
    for (int v : graph[u]) {
        if(v^pre) {
            pair<int,int> sub = dfs(v,u);
            sub.second++;
            if(maximize(ret.second,sub.second)) {
                ret = sub;
            }
        }
    }
    return ret;
}

int calc(int node) {
    int far = dfs(node,-1).first;
    return dfs(far,-1).second;
}

signed main() {
    ccps();
    cin >> n >> m;
    mset(visited,false);
    int res = 0;
    for (int i = 1; i<=m; i++) {
        int u,v; cin >> u >> v;
        graph[u].push_back(v);
        graph[v].push_back(u);
    }
    for (int u = 1; u<=n; u++) {
        if(!visited[u]) {
            res+=calc(u);
        }
    }
    cout << res;
}

Compilation message (stderr)

Main.cpp: In function 'void ccps()':
Main.cpp:26:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   26 |         freopen(NAME".inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
Main.cpp:27:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |         freopen(NAME".out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 15 / 15
• Subtask 2: 6 / 6
• Subtask 3: 6 / 6
• Subtask 4: 15 / 15
• Subtask 5: 28 / 28