제출 #647076

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
647076		Alma	Cijanobakterije (COCI21_cijanobakterije)	C++14	70 / 70	50 ms	7500 KiB

Main

#include <bits/stdc++.h>
using namespace std;

#define fi first
#define se second
using ll = long long;
using ii = pair<int,int>;

const int INF = 1e9;
const ll LLINF = 1e18;
using vi = vector<int>;
using vvi = vector<vi>;

void setIO (string fileName) {
    ios::sync_with_stdio(false);
    cin.tie(NULL);
    if (fileName != "std") {
        freopen((fileName + ".in").c_str(), "r", stdin);
        freopen((fileName + ".out").c_str(), "w", stdout);
    }
}

int treeDiameter (vvi& adj, vi& vis, int idx) {
	int last = idx, dist = 1;
	queue<ii> bfs;
	bfs.push({idx, -1});
	while (!bfs.empty()) {
		int u = bfs.front().fi;
		int p = bfs.front().se;
		bfs.pop();
		last = u;
		for (int v: adj[u]) {
			if (v != p) bfs.push({v, u});
		}
	}
	bfs.push({last, 1});
	while (!bfs.empty()) {
		int u = bfs.front().fi;
		int d = bfs.front().se;
		bfs.pop();
		dist = d;
		vis[u] = true;
		for (int v: adj[u]) {
			if (!vis[v]) bfs.push({v, d+1});
		}
	}
	return dist;
}

int main() {
    setIO("std");

    int n, m, u, v;
	cin >> n >> m;
	vvi adj(n);
	vi vis(n, false);

	while (m--) {
		cin >> u >> v;
		u--; v--;
		adj[u].push_back(v);
		adj[v].push_back(u);
	}

	int ans = 0;
	for (int i = 0; i < n; i++) {
		if (!vis[i]) {
			ans += treeDiameter(adj, vis, i);
		}
	}
	cout << ans << '\n';

    return 0;
}

컴파일 시 표준 에러 (stderr) 메시지

Main.cpp: In function 'void setIO(std::string)':
Main.cpp:18:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   18 |         freopen((fileName + ".in").c_str(), "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:19:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   19 |         freopen((fileName + ".out").c_str(), "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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