Submission #863795

#	Time	Username	Problem	Language	Result	Execution time	Memory
863795		Trisanu_Das	Newspapers (CEOI21_newspapers)	C++17	100 / 100	2 ms	604 KiB

newspapers

#include <bits/stdc++.h>
using namespace std;
 
const int maxn = 1010;
int n, m, d[maxn], pre[maxn];
vector<int> path, ans, G[maxn];
 
int main() {
    cin >> n >> m;
    if (m >= n) puts("NO"), exit(0);
    if (n == 1) puts("YES\n1\n1"), exit(0);
    if (n == 2) puts("YES\n2\n1 1"), exit(0);
    while (m--) {
        int u, v; cin >> u >> v;
        G[u].push_back(v), G[v].push_back(u);
    }
    auto bfs = [&]() {
        queue<int> Q;
        for (int i = 1; i <= n; i++) if (!d[i]) Q.push(i);
        while (!Q.empty()) {
            int u = Q.front(); Q.pop();
            for (int v : G[u]) if (!~d[v]) Q.push(v), d[v] = d[u] + 1, pre[v] = u;
        }
    };
    memset(d, -1, sizeof(d));
    d[1] = 0, bfs();
    int s = max_element(d + 1, d + n + 1) - d;
    memset(d, -1, sizeof(d));
    d[s] = 0, bfs();
    int t = max_element(d + 1, d + n + 1) - d;
    for (int i = t; i ^ s; i = pre[i]) path.push_back(i);
    path.push_back(s);
    memset(d, -1, sizeof(d));
    for (int i : path) d[i] = 0;
    bfs();
    if (*max_element(d + 1, d + n + 1) > 2) puts("NO"), exit(0);
    for (int i = 1; i + 1 < path.size(); i++) {
        for (int j : G[path[i]]) if (d[j] && G[j].size() > 1) ans.push_back(path[i]), ans.push_back(j);
        ans.push_back(path[i]);
    }
    printf("YES\n%d\n", 2 * ans.size());
    for (int x : ans) printf("%d ", x);
    reverse(ans.begin(), ans.end());
    for (int x : ans) printf("%d ", x);
}

Compilation message (stderr)

newspapers.cpp: In function 'int main()':
newspapers.cpp:37:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   37 |     for (int i = 1; i + 1 < path.size(); i++) {
      |                     ~~~~~~^~~~~~~~~~~~~
newspapers.cpp:41:19: warning: format '%d' expects argument of type 'int', but argument 2 has type 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wformat=]
   41 |     printf("YES\n%d\n", 2 * ans.size());
      |                  ~^     ~~~~~~~~~~~~~~
      |                   |       |
      |                   int     std::vector<int>::size_type {aka long unsigned int}
      |                  %ld

• Subtask 1: 12 / 12
• Subtask 2: 8 / 8
• Subtask 3: 80 / 80