///
#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
//#include "temp.cpp"
#include <cstdio>
using namespace std;
#ifndef ONLINE_JUDGE
#define dbg(x) cerr << #x <<" "; print(x); cerr << endl;
#else
#define dbg(x)
#endif
#define sz(x) (int)x.size()
#define len(x) (int)x.length()
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define clr(x) (x).clear()
#define uniq(x) x.resize(unique(all(x)) - x.begin());
#define blt __builtin_popcount
#define pb push_back
#define popf pop_front
#define popb pop_back
#define ld long double
void print(long long t) {cerr << t;}
void print(int t) {cerr << t;}
void print(string t) {cerr << t;}
void print(char t) {cerr << t;}
void print(double t) {cerr << t;}
void print(long double t) {cerr << t;}
void print(unsigned long long t) {cerr << t;}
template <class T, class V> void print(pair <T, V> p);
template <class T> void print(vector <T> v);
template <class T> void print(set <T> v);
template <class T, class V> void print(map <T, V> v);
template <class T> void print(multiset <T> v);
template <class T, class V> void print(T v[],V n) {cerr << "["; for(int i = 0; i < n; i++) {print(v[i]); cerr << " "; } cerr << "]";}
template <class T, class V> void print(pair <T, V> p) {cerr << "{"; print(p.first); cerr << ","; print(p.second); cerr << "}";}
template <class T> void print(vector <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(set <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(multiset <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T, class V> void print(map <T, V> v) {cerr << "[ "; for (auto i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(deque <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
#define nl '\n'
// for random generations
// mt19937 myrand(chrono::steady_clock::now().time_since_epoch().count());
mt19937 myrand(373);
// for grid problems
int dx[8] = {-1,0,1,0,1,-1,1,-1};
int dy[8] = {0,1,0,-1,1,1,-1,-1};
// lowest / (1 << 17) >= 1e5 / (1 << 18) >= 2e5 / (1 << 21) >= 1e6
void fastIO() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr); cout.tie(nullptr);
}
// file in/out
void setIO(string str = "") {
fastIO();
if(str == "input") {
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
} else {
// freopen("skis.in", "r", stdin);
// freopen("skis.out", "w", stdout);
}
}
// Indexed Set
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
const int N = 1005;
vector<int> adj[N];
int vis[N];
int n, m, dp[N];
int ok = 1;
void dfs1(int node, int parent) {
dp[node] = 1;
int ci = 0;
for(auto i: adj[node]) {
if(i == parent) continue;
dfs1(i, node);
dp[node] = max(dp[node], dp[i] + 1);
if(dp[i] >= 3) {
ci++;
}
}
if(ci >= 3) {
ok = 0;
}
}
void dfs2(int node, int parent, int up = 0) {
multiset<int> mt;
int ci = 0;
if(up >= 3) {
ci++;
}
for(auto i: adj[node]) {
if(i == parent) continue;
mt.insert(dp[i]);
if(dp[i] >= 3) {
ci++;
}
}
if(ci >= 3) {
ok = 0;
}
for(auto i: adj[node]) {
if(i == parent) continue;
mt.erase(dp[i]);
if(mt.empty()) {
dfs2(i, node, up + 1);
} else {
dfs2(i, node, *mt.rbegin() + 1);
}
mt.insert(dp[i]);
}
}
void solve_() {
cin >> n >> m;
if(m > n - 1) {
cout << "NO" << endl;
return;
}
int ok = 1, g = -1;
if(m != n - 1) {
ok = 0;
}
vector<int> deg(n + 1);
for(int i = 1; i <= m; i++) {
int a, b; cin >> a >> b;
adj[a].push_back(b);
adj[b].push_back(a);
if(a > b) {
swap(a, b);
}
if(ok && b != (a + 1)) {
ok = 0;
}
deg[a]++, deg[b]++;
if(deg[a] >= 2) {
g = a;
}
if(deg[b] >= 2) {
g = a;
}
}
int ok2 = 0;
for(int i = 1; i <= n; i++) {
ok = 1;
dfs1(i, 0);
dfs2(i, 0);
if(ok) {
ok2 = 1;
cout << "YES" << '\n';
break;
}
}
if(!ok2) {
cout << "NO" << '\n';
return;
}
if(n == 1) {
cout << 1 << '\n';
cout << 1 << '\n';
} else if(n == 2) {
cout << 2 << '\n';
cout << 1 << " " << 1 << '\n';
} else if(n == 3) {
cout << 2 << '\n';
cout << g << " " << g << '\n';
} else if(ok) {
cout << 2 * (n - 2) << '\n';
for(int i = 2; i < n; i++) {
cout << i << " ";
}
for(int i = n - 1; i >= 2; i--) {
cout << i << " ";
}
cout << '\n';
}
}
int main() {
setIO();
auto solve = [&](int test_case)-> void {
for(int i = 1; i <= test_case; i++) {
solve_();
}
};
int test_cases = 1;
// cin >> test_cases;
solve(test_cases);
return 0;
}
Compilation message
newspapers.cpp: In function 'void setIO(std::string)':
newspapers.cpp:70:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
70 | freopen("input.txt", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
newspapers.cpp:71:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
71 | freopen("output.txt", "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
352 KB |
Output is correct |
| 2 |
Correct |
1 ms |
340 KB |
Output is correct |
| 3 |
Correct |
1 ms |
356 KB |
Output is correct |
| 4 |
Correct |
1 ms |
348 KB |
Output is correct |
| 5 |
Partially correct |
1 ms |
348 KB |
Failed to provide a successful strategy. |
| 6 |
Partially correct |
1 ms |
340 KB |
Failed to provide a successful strategy. |
| 7 |
Correct |
1 ms |
352 KB |
Output is correct |
| 8 |
Partially correct |
1 ms |
340 KB |
Failed to provide a successful strategy. |
| 9 |
Incorrect |
1 ms |
340 KB |
Output isn't correct |
| 10 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
340 KB |
Output is correct |
| 2 |
Correct |
1 ms |
340 KB |
Output is correct |
| 3 |
Correct |
1 ms |
356 KB |
Output is correct |
| 4 |
Correct |
1 ms |
340 KB |
Output is correct |
| 5 |
Correct |
1 ms |
340 KB |
Output is correct |
| 6 |
Correct |
1 ms |
340 KB |
Output is correct |
| 7 |
Correct |
0 ms |
340 KB |
Output is correct |
| 8 |
Correct |
1 ms |
340 KB |
Output is correct |
| 9 |
Correct |
1 ms |
340 KB |
Output is correct |
| 10 |
Correct |
1 ms |
340 KB |
Output is correct |
| 11 |
Correct |
1 ms |
468 KB |
Output is correct |
| 12 |
Correct |
1 ms |
352 KB |
Output is correct |
| 13 |
Correct |
1 ms |
468 KB |
Output is correct |
| 14 |
Correct |
1 ms |
468 KB |
Output is correct |
| 15 |
Correct |
1 ms |
468 KB |
Output is correct |
| 16 |
Correct |
1 ms |
468 KB |
Output is correct |
| 17 |
Correct |
1 ms |
468 KB |
Output is correct |
| 18 |
Correct |
1 ms |
468 KB |
Output is correct |
| 19 |
Correct |
1 ms |
468 KB |
Output is correct |
| 20 |
Correct |
1 ms |
468 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
352 KB |
Output is correct |
| 2 |
Correct |
1 ms |
340 KB |
Output is correct |
| 3 |
Correct |
1 ms |
356 KB |
Output is correct |
| 4 |
Correct |
1 ms |
348 KB |
Output is correct |
| 5 |
Partially correct |
1 ms |
348 KB |
Failed to provide a successful strategy. |
| 6 |
Partially correct |
1 ms |
340 KB |
Failed to provide a successful strategy. |
| 7 |
Correct |
1 ms |
352 KB |
Output is correct |
| 8 |
Partially correct |
1 ms |
340 KB |
Failed to provide a successful strategy. |
| 9 |
Incorrect |
1 ms |
340 KB |
Output isn't correct |
| 10 |
Halted |
0 ms |
0 KB |
- |
