#include <bits/stdc++.h>
using namespace std;
#define int long long
#define FOR(i,s,e) for(int i = s; i <= (int)e; ++i)
#define DEC(i,s,e) for(int i = s; i >= (int)e; --i)
#define IAMSPEED ios_base::sync_with_stdio(false); cin.tie(0);
#ifdef LOCAL
#define db(x) cerr << #x << "=" << x << "\n"
#define db2(x, y) cerr << #x << "=" << x << " , " << #y << "=" << y << "\n"
#define db3(a,b,c) cerr<<#a<<"="<<a<<","<<#b<<"="<<b<<","<<#c<<"="<<c<<"\n"
#define dbv(v) cerr << #v << ":"; for (auto ite : v) cerr << ite << ' '; cerr <<"\n"
#define dbvp(v) cerr << #v << ":"; for (auto ite : v) cerr << "{" << ite.f << ',' << ite.s << "} "; cerr << "\n"
#define dba(a,ss,ee) cerr << #a << ":"; FOR(ite,ss,ee) cerr << a[ite] << ' '; cerr << "\n"
#define reach cerr << "LINE: " << __LINE__ << "\n";
#else
#define reach
#define db(x)
#define db2(x,y)
#define db3(a,b,c)
#define dbv(v)
#define dbvp(v)
#define dba(a,ss,ee)
#endif
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define pb push_back
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define f first
#define s second
#define g0(x) get<0>(x)
#define g1(x) get<1>(x)
#define g2(x) get<2>(x)
#define g3(x) get<3>(x)
typedef pair <int, int> pi;
typedef tuple<int,int,int> ti3;
typedef tuple<int,int,int,int> ti4;
int rand(int a, int b) { return a + rng() % (b-a+1); }
const int MOD = 1e9 + 7;
const int inf = (int)1e9 + 500;
const long long oo = (long long)1e18 + 500;
template <typename T> bool chmax(T& a, const T b) { return a<b ? a = b, 1 : 0; }
template <typename T> bool chmin(T& a, const T b) { return a>b ? a = b, 1 : 0; }
const int MAXN = -1;
vector<int> V[1005];
int n,m;
int dist[1005];
pi bfs(int source) {
memset(dist,-1,sizeof dist);
queue<int> q;
dist[source]=0;
q.push(source);
while(q.size()) {
int x=q.front(); q.pop();
for(auto v:V[x]){
if(dist[v]==-1 || dist[v]>dist[x]+1) {
dist[v]=dist[x]+1;
q.push(v);
}
}
}
pi mx=pi(0,0);
FOR(i,1,n) {
chmax(mx,{dist[i],i});
}
return mx;
}
int dfs(int x, int p) {
int l=1;
for(auto v:V[x])if(v!=p) {
int res=dfs(v,x);
chmax(l,res+1);
}
return l;
}
int32_t main()
{
IAMSPEED
cin >> n >> m;
if(n==1) {
return cout << "YES\n1 \n1", 0;
} else if(n==2) {
return cout << "YES\n2 \n1 1", 0;
}
if(m!=(n-1)) return cout << "NO\n", 0; // cycle=cannot
/*
cout << "YES\n";
cout << 2*(n-2) << '\n';
FOR(i,2,n-1) cout << i << ' ';
DEC(i,n-1,2) cout << i << ' ';
*/
FOR(i,1,n-1){
int a,b; cin >> a >> b;
V[a].pb(b);
V[b].pb(a);
}
pi r=bfs(1);
int src=r.s;
int sink=bfs(src).s;
vector<int> path;
path.pb(sink);
while(path.back() != src) {
int x=path.back();
for(auto v:V[x]){
if(dist[v]==dist[x]-1){
path.pb(v);
break;
}
}
}
int S=path.size();
dbv(path);
if(S==2||S==3) {
return cout << "YES\n2 \n" << path[S/2] << ' ' << path[S/2], 0;
}
vector<int> ans;
ans.pb(path[1]);
FOR(i,2,path.size()-3) {
int x=path[i];
int pre=path[i-1];
int nxt=path[i+1];
vector<int> here;
for(auto v:V[x]) {
if(v==pre||v==nxt)continue;
db(v);
int l=dfs(v,x);
if(l>2) {
cout << "NO\n"; exit(0);
}
db(l);
if(l==2) {
here.pb(v);
} // if not, either of the iterations will cover it anyways?
}
ans.pb(x);
for(auto i:here) {
ans.pb(i);
ans.pb(x);
}
}
ans.pb(path[S-2]);
// now for the return.
ans.pb(path[S-2]);
DEC(i,path.size()-3,2) {
int x=path[i];
int pre=path[i+1];
int nxt=path[i-1];
vector<int> here;
for(auto v:V[x]) {
if(v==pre||v==nxt)continue;
int l=dfs(v,x);
db(l);
if(l>2) {
cout << "NO\n"; exit(0);
}
if(l==2) {
here.pb(v);
} // if not, either of the iterations will cover it anyways?
}
ans.pb(x);
for(auto i:here) {
ans.pb(i);
ans.pb(x);
}
}
cout << "YES\n";
ans.pb(path[1]);
cout << ans.size() << '\n';
for(auto i:ans)cout<<i<<' ';
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
340 KB |
Output is correct |
2 |
Correct |
0 ms |
340 KB |
Output is correct |
3 |
Correct |
1 ms |
340 KB |
Output is correct |
4 |
Correct |
1 ms |
340 KB |
Output is correct |
5 |
Correct |
0 ms |
340 KB |
Output is correct |
6 |
Correct |
0 ms |
340 KB |
Output is correct |
7 |
Correct |
0 ms |
340 KB |
Output is correct |
8 |
Correct |
0 ms |
340 KB |
Output is correct |
9 |
Correct |
1 ms |
348 KB |
Output is correct |
10 |
Correct |
1 ms |
340 KB |
Output is correct |
11 |
Correct |
1 ms |
340 KB |
Output is correct |
12 |
Correct |
1 ms |
340 KB |
Output is correct |
13 |
Correct |
1 ms |
340 KB |
Output is correct |
14 |
Correct |
0 ms |
340 KB |
Output is correct |
15 |
Correct |
1 ms |
340 KB |
Output is correct |
16 |
Correct |
1 ms |
340 KB |
Output is correct |
17 |
Correct |
1 ms |
340 KB |
Output is correct |
18 |
Correct |
0 ms |
340 KB |
Output is correct |
19 |
Correct |
1 ms |
340 KB |
Output is correct |
20 |
Correct |
0 ms |
340 KB |
Output is correct |
21 |
Correct |
1 ms |
340 KB |
Output is correct |
22 |
Correct |
0 ms |
352 KB |
Output is correct |
23 |
Correct |
1 ms |
340 KB |
Output is correct |
24 |
Correct |
1 ms |
340 KB |
Output is correct |
25 |
Correct |
1 ms |
340 KB |
Output is correct |
26 |
Correct |
1 ms |
340 KB |
Output is correct |
27 |
Correct |
1 ms |
352 KB |
Output is correct |
28 |
Correct |
1 ms |
340 KB |
Output is correct |
29 |
Correct |
1 ms |
340 KB |
Output is correct |
30 |
Correct |
0 ms |
348 KB |
Output is correct |
31 |
Correct |
1 ms |
340 KB |
Output is correct |
32 |
Correct |
1 ms |
432 KB |
Output is correct |
33 |
Correct |
1 ms |
340 KB |
Output is correct |
34 |
Correct |
0 ms |
352 KB |
Output is correct |
35 |
Correct |
0 ms |
340 KB |
Output is correct |
36 |
Correct |
1 ms |
340 KB |
Output is correct |
37 |
Correct |
1 ms |
340 KB |
Output is correct |
38 |
Correct |
1 ms |
348 KB |
Output is correct |
39 |
Correct |
1 ms |
340 KB |
Output is correct |
40 |
Correct |
1 ms |
340 KB |
Output is correct |
41 |
Correct |
1 ms |
340 KB |
Output is correct |
42 |
Correct |
0 ms |
340 KB |
Output is correct |
43 |
Correct |
1 ms |
340 KB |
Output is correct |
44 |
Correct |
1 ms |
340 KB |
Output is correct |
45 |
Correct |
1 ms |
340 KB |
Output is correct |
46 |
Correct |
0 ms |
348 KB |
Output is correct |
47 |
Correct |
0 ms |
340 KB |
Output is correct |
48 |
Correct |
0 ms |
340 KB |
Output is correct |
49 |
Correct |
1 ms |
340 KB |
Output is correct |
50 |
Correct |
1 ms |
340 KB |
Output is correct |
51 |
Correct |
0 ms |
340 KB |
Output is correct |
52 |
Correct |
1 ms |
340 KB |
Output is correct |
53 |
Correct |
1 ms |
340 KB |
Output is correct |
54 |
Correct |
1 ms |
340 KB |
Output is correct |
55 |
Correct |
1 ms |
340 KB |
Output is correct |
56 |
Correct |
1 ms |
340 KB |
Output is correct |
57 |
Correct |
1 ms |
340 KB |
Output is correct |
58 |
Correct |
1 ms |
340 KB |
Output is correct |
59 |
Correct |
0 ms |
352 KB |
Output is correct |
60 |
Correct |
0 ms |
340 KB |
Output is correct |
61 |
Correct |
1 ms |
340 KB |
Output is correct |
62 |
Correct |
1 ms |
340 KB |
Output is correct |
63 |
Correct |
1 ms |
340 KB |
Output is correct |
64 |
Correct |
0 ms |
340 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
340 KB |
Output is correct |
2 |
Correct |
0 ms |
340 KB |
Output is correct |
3 |
Correct |
0 ms |
340 KB |
Output is correct |
4 |
Correct |
0 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 |
0 ms |
340 KB |
Output is correct |
9 |
Correct |
0 ms |
340 KB |
Output is correct |
10 |
Correct |
0 ms |
340 KB |
Output is correct |
11 |
Correct |
1 ms |
340 KB |
Output is correct |
12 |
Correct |
1 ms |
340 KB |
Output is correct |
13 |
Correct |
1 ms |
340 KB |
Output is correct |
14 |
Correct |
1 ms |
340 KB |
Output is correct |
15 |
Correct |
1 ms |
340 KB |
Output is correct |
16 |
Correct |
1 ms |
340 KB |
Output is correct |
17 |
Correct |
1 ms |
340 KB |
Output is correct |
18 |
Correct |
1 ms |
340 KB |
Output is correct |
19 |
Correct |
1 ms |
340 KB |
Output is correct |
20 |
Correct |
1 ms |
340 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
340 KB |
Output is correct |
2 |
Correct |
0 ms |
340 KB |
Output is correct |
3 |
Correct |
1 ms |
340 KB |
Output is correct |
4 |
Correct |
1 ms |
340 KB |
Output is correct |
5 |
Correct |
0 ms |
340 KB |
Output is correct |
6 |
Correct |
0 ms |
340 KB |
Output is correct |
7 |
Correct |
0 ms |
340 KB |
Output is correct |
8 |
Correct |
0 ms |
340 KB |
Output is correct |
9 |
Correct |
1 ms |
348 KB |
Output is correct |
10 |
Correct |
1 ms |
340 KB |
Output is correct |
11 |
Correct |
1 ms |
340 KB |
Output is correct |
12 |
Correct |
1 ms |
340 KB |
Output is correct |
13 |
Correct |
1 ms |
340 KB |
Output is correct |
14 |
Correct |
0 ms |
340 KB |
Output is correct |
15 |
Correct |
1 ms |
340 KB |
Output is correct |
16 |
Correct |
1 ms |
340 KB |
Output is correct |
17 |
Correct |
1 ms |
340 KB |
Output is correct |
18 |
Correct |
0 ms |
340 KB |
Output is correct |
19 |
Correct |
1 ms |
340 KB |
Output is correct |
20 |
Correct |
0 ms |
340 KB |
Output is correct |
21 |
Correct |
1 ms |
340 KB |
Output is correct |
22 |
Correct |
0 ms |
352 KB |
Output is correct |
23 |
Correct |
1 ms |
340 KB |
Output is correct |
24 |
Correct |
1 ms |
340 KB |
Output is correct |
25 |
Correct |
1 ms |
340 KB |
Output is correct |
26 |
Correct |
1 ms |
340 KB |
Output is correct |
27 |
Correct |
1 ms |
352 KB |
Output is correct |
28 |
Correct |
1 ms |
340 KB |
Output is correct |
29 |
Correct |
1 ms |
340 KB |
Output is correct |
30 |
Correct |
0 ms |
348 KB |
Output is correct |
31 |
Correct |
1 ms |
340 KB |
Output is correct |
32 |
Correct |
1 ms |
432 KB |
Output is correct |
33 |
Correct |
1 ms |
340 KB |
Output is correct |
34 |
Correct |
0 ms |
352 KB |
Output is correct |
35 |
Correct |
0 ms |
340 KB |
Output is correct |
36 |
Correct |
1 ms |
340 KB |
Output is correct |
37 |
Correct |
1 ms |
340 KB |
Output is correct |
38 |
Correct |
1 ms |
348 KB |
Output is correct |
39 |
Correct |
1 ms |
340 KB |
Output is correct |
40 |
Correct |
1 ms |
340 KB |
Output is correct |
41 |
Correct |
1 ms |
340 KB |
Output is correct |
42 |
Correct |
0 ms |
340 KB |
Output is correct |
43 |
Correct |
1 ms |
340 KB |
Output is correct |
44 |
Correct |
1 ms |
340 KB |
Output is correct |
45 |
Correct |
1 ms |
340 KB |
Output is correct |
46 |
Correct |
0 ms |
348 KB |
Output is correct |
47 |
Correct |
0 ms |
340 KB |
Output is correct |
48 |
Correct |
0 ms |
340 KB |
Output is correct |
49 |
Correct |
1 ms |
340 KB |
Output is correct |
50 |
Correct |
1 ms |
340 KB |
Output is correct |
51 |
Correct |
0 ms |
340 KB |
Output is correct |
52 |
Correct |
1 ms |
340 KB |
Output is correct |
53 |
Correct |
1 ms |
340 KB |
Output is correct |
54 |
Correct |
1 ms |
340 KB |
Output is correct |
55 |
Correct |
1 ms |
340 KB |
Output is correct |
56 |
Correct |
1 ms |
340 KB |
Output is correct |
57 |
Correct |
1 ms |
340 KB |
Output is correct |
58 |
Correct |
1 ms |
340 KB |
Output is correct |
59 |
Correct |
0 ms |
352 KB |
Output is correct |
60 |
Correct |
0 ms |
340 KB |
Output is correct |
61 |
Correct |
1 ms |
340 KB |
Output is correct |
62 |
Correct |
1 ms |
340 KB |
Output is correct |
63 |
Correct |
1 ms |
340 KB |
Output is correct |
64 |
Correct |
0 ms |
340 KB |
Output is correct |
65 |
Correct |
1 ms |
340 KB |
Output is correct |
66 |
Correct |
0 ms |
340 KB |
Output is correct |
67 |
Correct |
0 ms |
348 KB |
Output is correct |
68 |
Correct |
1 ms |
340 KB |
Output is correct |
69 |
Correct |
1 ms |
340 KB |
Output is correct |
70 |
Correct |
1 ms |
340 KB |
Output is correct |
71 |
Correct |
1 ms |
340 KB |
Output is correct |
72 |
Correct |
1 ms |
340 KB |
Output is correct |
73 |
Correct |
1 ms |
340 KB |
Output is correct |
74 |
Correct |
1 ms |
340 KB |
Output is correct |
75 |
Correct |
1 ms |
340 KB |
Output is correct |
76 |
Correct |
1 ms |
340 KB |
Output is correct |
77 |
Correct |
1 ms |
340 KB |
Output is correct |
78 |
Correct |
1 ms |
340 KB |
Output is correct |
79 |
Correct |
1 ms |
340 KB |
Output is correct |
80 |
Correct |
1 ms |
340 KB |
Output is correct |
81 |
Correct |
1 ms |
340 KB |
Output is correct |
82 |
Correct |
1 ms |
356 KB |
Output is correct |
83 |
Correct |
1 ms |
340 KB |
Output is correct |
84 |
Correct |
1 ms |
340 KB |
Output is correct |
85 |
Correct |
1 ms |
340 KB |
Output is correct |
86 |
Correct |
1 ms |
340 KB |
Output is correct |
87 |
Correct |
1 ms |
356 KB |
Output is correct |
88 |
Correct |
1 ms |
340 KB |
Output is correct |
89 |
Correct |
1 ms |
340 KB |
Output is correct |
90 |
Correct |
1 ms |
340 KB |
Output is correct |
91 |
Correct |
1 ms |
348 KB |
Output is correct |
92 |
Correct |
1 ms |
340 KB |
Output is correct |
93 |
Correct |
1 ms |
340 KB |
Output is correct |
94 |
Correct |
1 ms |
356 KB |
Output is correct |
95 |
Correct |
1 ms |
340 KB |
Output is correct |
96 |
Correct |
1 ms |
340 KB |
Output is correct |
97 |
Correct |
1 ms |
340 KB |
Output is correct |
98 |
Correct |
1 ms |
340 KB |
Output is correct |
99 |
Correct |
1 ms |
340 KB |
Output is correct |
100 |
Correct |
1 ms |
340 KB |
Output is correct |
101 |
Correct |
1 ms |
340 KB |
Output is correct |
102 |
Correct |
1 ms |
340 KB |
Output is correct |
103 |
Correct |
1 ms |
340 KB |
Output is correct |
104 |
Correct |
1 ms |
340 KB |
Output is correct |
105 |
Correct |
1 ms |
340 KB |
Output is correct |
106 |
Correct |
1 ms |
360 KB |
Output is correct |
107 |
Correct |
1 ms |
340 KB |
Output is correct |
108 |
Correct |
1 ms |
340 KB |
Output is correct |
109 |
Correct |
1 ms |
340 KB |
Output is correct |
110 |
Correct |
1 ms |
340 KB |
Output is correct |
111 |
Correct |
1 ms |
340 KB |
Output is correct |
112 |
Correct |
1 ms |
340 KB |
Output is correct |
113 |
Correct |
1 ms |
340 KB |
Output is correct |
114 |
Correct |
1 ms |
468 KB |
Output is correct |
115 |
Correct |
1 ms |
356 KB |
Output is correct |
116 |
Correct |
1 ms |
340 KB |
Output is correct |
117 |
Correct |
1 ms |
360 KB |
Output is correct |
118 |
Correct |
1 ms |
340 KB |
Output is correct |
119 |
Correct |
1 ms |
340 KB |
Output is correct |
120 |
Correct |
1 ms |
340 KB |
Output is correct |
121 |
Correct |
1 ms |
424 KB |
Output is correct |
122 |
Correct |
1 ms |
340 KB |
Output is correct |
123 |
Correct |
1 ms |
340 KB |
Output is correct |
124 |
Correct |
1 ms |
340 KB |
Output is correct |
125 |
Correct |
1 ms |
340 KB |
Output is correct |
126 |
Correct |
1 ms |
340 KB |
Output is correct |
127 |
Correct |
1 ms |
352 KB |
Output is correct |
128 |
Correct |
1 ms |
340 KB |
Output is correct |
129 |
Correct |
1 ms |
352 KB |
Output is correct |
130 |
Correct |
1 ms |
340 KB |
Output is correct |
131 |
Correct |
1 ms |
340 KB |
Output is correct |
132 |
Correct |
1 ms |
340 KB |
Output is correct |
133 |
Correct |
1 ms |
356 KB |
Output is correct |
134 |
Correct |
1 ms |
368 KB |
Output is correct |
135 |
Correct |
1 ms |
364 KB |
Output is correct |
136 |
Correct |
1 ms |
340 KB |
Output is correct |
137 |
Correct |
1 ms |
340 KB |
Output is correct |
138 |
Correct |
0 ms |
340 KB |
Output is correct |
139 |
Correct |
1 ms |
340 KB |
Output is correct |
140 |
Correct |
1 ms |
340 KB |
Output is correct |
141 |
Correct |
1 ms |
340 KB |
Output is correct |
142 |
Correct |
1 ms |
340 KB |
Output is correct |
143 |
Correct |
1 ms |
340 KB |
Output is correct |
144 |
Correct |
1 ms |
340 KB |
Output is correct |
145 |
Correct |
1 ms |
356 KB |
Output is correct |