Submission #711678

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
711678	2023-03-17T11:04:12 Z	Pherokung	Network (BOI15_net)	C++14	100 / 100	472 ms	65396 KB

#include<bits/stdc++.h>
using namespace std;
#define MAXN 500005
#define pb push_back
#define F first
#define S second
typedef pair<int,int> pa;
int n,u,v,top;
vector<int> adj[MAXN];
vector<pa> ans;

pa merge(pa A, pa B){
	if(A == make_pair(-1,-1)) return B;
	if(B == make_pair(-1,-1)) return A;
	if(A.S == - 1 && B.S == -1) return {A.F,B.F};
	if(A.S != -1 && B.S != -1){
		ans.push_back({A.S,B.S});
		return {A.F,B.F};
	}
	if(A.S != -1){
		ans.push_back({A.S,B.F});
		return {A.F,-1};
	}
	if(B.S != -1){
		ans.push_back({B.S,A.F});
		return {B.F,-1};
	}
}

pa dfs(int u,int p){
	pa val = (adj[u][0] == p && adj[u].size() == 1) ? make_pair(u,-1) : make_pair(-1,-1);
	for(auto v : adj[u]){
		if(v == p) continue;
		val = merge(val,dfs(v,u));
	}
	//printf("!! %d : %d %d\n",u,val.F,val.S);
	return val;
}

int main(){
	scanf("%d",&n);
	for(int i=1;i<n;i++){
		scanf("%d%d",&u,&v);
		adj[u].pb(v), adj[v].pb(u);
	}
	
	for(int i=1;i<=n;i++) if(adj[i].size() > 1) top = i;
	pa val = dfs(top,top);
	if(val.F != -1 && val.S != -1) ans.push_back({val.F,val.S});
	else if(val.F != -1) ans.push_back({val.F,top});
	
	printf("%d\n",ans.size());
	for(auto x : ans) printf("%d %d\n",x.F,x.S);
}

Compilation message

net.cpp: In function 'int main()':
net.cpp:52:11: warning: format '%d' expects argument of type 'int', but argument 2 has type 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wformat=]
   52 |  printf("%d\n",ans.size());
      |          ~^    ~~~~~~~~~~
      |           |            |
      |           int          std::vector<std::pair<int, int> >::size_type {aka long unsigned int}
      |          %ld
net.cpp: In function 'pa merge(pa, pa)':
net.cpp:28:1: warning: control reaches end of non-void function [-Wreturn-type]
   28 | }
      | ^
net.cpp: In function 'int main()':
net.cpp:41:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   41 |  scanf("%d",&n);
      |  ~~~~~^~~~~~~~~
net.cpp:43:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   43 |   scanf("%d%d",&u,&v);
      |   ~~~~~^~~~~~~~~~~~~~

Subtask #1
18.0 / 18.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	8 ms	11988 KB	Output is correct
2	Correct	7 ms	12044 KB	Output is correct
3	Correct	7 ms	12044 KB	Output is correct
4	Correct	7 ms	11988 KB	Output is correct
5	Correct	6 ms	11988 KB	Output is correct
6	Correct	7 ms	11988 KB	Output is correct
7	Correct	7 ms	11988 KB	Output is correct
8	Correct	7 ms	12028 KB	Output is correct
9	Correct	6 ms	12156 KB	Output is correct
10	Correct	7 ms	12044 KB	Output is correct
11	Correct	7 ms	11988 KB	Output is correct
12	Correct	7 ms	11988 KB	Output is correct
13	Correct	8 ms	12048 KB	Output is correct
14	Correct	7 ms	11988 KB	Output is correct
15	Correct	8 ms	11988 KB	Output is correct
16	Correct	7 ms	12016 KB	Output is correct
17	Correct	7 ms	11948 KB	Output is correct
18	Correct	7 ms	11968 KB	Output is correct
19	Correct	7 ms	12044 KB	Output is correct
20	Correct	7 ms	12044 KB	Output is correct

Subtask #2
45.0 / 45.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	8 ms	11988 KB	Output is correct
2	Correct	7 ms	12044 KB	Output is correct
3	Correct	7 ms	12044 KB	Output is correct
4	Correct	7 ms	11988 KB	Output is correct
5	Correct	6 ms	11988 KB	Output is correct
6	Correct	7 ms	11988 KB	Output is correct
7	Correct	7 ms	11988 KB	Output is correct
8	Correct	7 ms	12028 KB	Output is correct
9	Correct	6 ms	12156 KB	Output is correct
10	Correct	7 ms	12044 KB	Output is correct
11	Correct	7 ms	11988 KB	Output is correct
12	Correct	7 ms	11988 KB	Output is correct
13	Correct	8 ms	12048 KB	Output is correct
14	Correct	7 ms	11988 KB	Output is correct
15	Correct	8 ms	11988 KB	Output is correct
16	Correct	7 ms	12016 KB	Output is correct
17	Correct	7 ms	11948 KB	Output is correct
18	Correct	7 ms	11968 KB	Output is correct
19	Correct	7 ms	12044 KB	Output is correct
20	Correct	7 ms	12044 KB	Output is correct
21	Correct	6 ms	11988 KB	Output is correct
22	Correct	8 ms	12140 KB	Output is correct
23	Correct	7 ms	12148 KB	Output is correct
24	Correct	9 ms	12116 KB	Output is correct
25	Correct	9 ms	12056 KB	Output is correct
26	Correct	9 ms	12116 KB	Output is correct
27	Correct	7 ms	12116 KB	Output is correct
28	Correct	8 ms	12068 KB	Output is correct
29	Correct	7 ms	12052 KB	Output is correct
30	Correct	6 ms	12040 KB	Output is correct
31	Correct	7 ms	12040 KB	Output is correct
32	Correct	7 ms	11988 KB	Output is correct
33	Correct	6 ms	11960 KB	Output is correct
34	Correct	7 ms	11988 KB	Output is correct
35	Correct	6 ms	12036 KB	Output is correct
36	Correct	6 ms	11988 KB	Output is correct
37	Correct	6 ms	12084 KB	Output is correct
38	Correct	7 ms	12116 KB	Output is correct
39	Correct	8 ms	12044 KB	Output is correct
40	Correct	8 ms	11988 KB	Output is correct
41	Correct	6 ms	12048 KB	Output is correct
42	Correct	7 ms	12048 KB	Output is correct
43	Correct	7 ms	11988 KB	Output is correct
44	Correct	7 ms	11988 KB	Output is correct
45	Correct	7 ms	11988 KB	Output is correct
46	Correct	7 ms	12064 KB	Output is correct
47	Correct	7 ms	11988 KB	Output is correct
48	Correct	7 ms	12044 KB	Output is correct
49	Correct	7 ms	12060 KB	Output is correct
50	Correct	6 ms	11988 KB	Output is correct
51	Correct	8 ms	11988 KB	Output is correct
52	Correct	7 ms	11988 KB	Output is correct
53	Correct	8 ms	11988 KB	Output is correct
54	Correct	7 ms	11988 KB	Output is correct
55	Correct	7 ms	11960 KB	Output is correct
56	Correct	7 ms	12044 KB	Output is correct
57	Correct	7 ms	11988 KB	Output is correct
58	Correct	7 ms	12056 KB	Output is correct

Subtask #3
37.0 / 37.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	8 ms	11988 KB	Output is correct
2	Correct	7 ms	12044 KB	Output is correct
3	Correct	7 ms	12044 KB	Output is correct
4	Correct	7 ms	11988 KB	Output is correct
5	Correct	6 ms	11988 KB	Output is correct
6	Correct	7 ms	11988 KB	Output is correct
7	Correct	7 ms	11988 KB	Output is correct
8	Correct	7 ms	12028 KB	Output is correct
9	Correct	6 ms	12156 KB	Output is correct
10	Correct	7 ms	12044 KB	Output is correct
11	Correct	7 ms	11988 KB	Output is correct
12	Correct	7 ms	11988 KB	Output is correct
13	Correct	8 ms	12048 KB	Output is correct
14	Correct	7 ms	11988 KB	Output is correct
15	Correct	8 ms	11988 KB	Output is correct
16	Correct	7 ms	12016 KB	Output is correct
17	Correct	7 ms	11948 KB	Output is correct
18	Correct	7 ms	11968 KB	Output is correct
19	Correct	7 ms	12044 KB	Output is correct
20	Correct	7 ms	12044 KB	Output is correct
21	Correct	6 ms	11988 KB	Output is correct
22	Correct	8 ms	12140 KB	Output is correct
23	Correct	7 ms	12148 KB	Output is correct
24	Correct	9 ms	12116 KB	Output is correct
25	Correct	9 ms	12056 KB	Output is correct
26	Correct	9 ms	12116 KB	Output is correct
27	Correct	7 ms	12116 KB	Output is correct
28	Correct	8 ms	12068 KB	Output is correct
29	Correct	7 ms	12052 KB	Output is correct
30	Correct	6 ms	12040 KB	Output is correct
31	Correct	7 ms	12040 KB	Output is correct
32	Correct	7 ms	11988 KB	Output is correct
33	Correct	6 ms	11960 KB	Output is correct
34	Correct	7 ms	11988 KB	Output is correct
35	Correct	6 ms	12036 KB	Output is correct
36	Correct	6 ms	11988 KB	Output is correct
37	Correct	6 ms	12084 KB	Output is correct
38	Correct	7 ms	12116 KB	Output is correct
39	Correct	8 ms	12044 KB	Output is correct
40	Correct	8 ms	11988 KB	Output is correct
41	Correct	6 ms	12048 KB	Output is correct
42	Correct	7 ms	12048 KB	Output is correct
43	Correct	7 ms	11988 KB	Output is correct
44	Correct	7 ms	11988 KB	Output is correct
45	Correct	7 ms	11988 KB	Output is correct
46	Correct	7 ms	12064 KB	Output is correct
47	Correct	7 ms	11988 KB	Output is correct
48	Correct	7 ms	12044 KB	Output is correct
49	Correct	7 ms	12060 KB	Output is correct
50	Correct	6 ms	11988 KB	Output is correct
51	Correct	8 ms	11988 KB	Output is correct
52	Correct	7 ms	11988 KB	Output is correct
53	Correct	8 ms	11988 KB	Output is correct
54	Correct	7 ms	11988 KB	Output is correct
55	Correct	7 ms	11960 KB	Output is correct
56	Correct	7 ms	12044 KB	Output is correct
57	Correct	7 ms	11988 KB	Output is correct
58	Correct	7 ms	12056 KB	Output is correct
59	Correct	338 ms	35960 KB	Output is correct
60	Correct	415 ms	38668 KB	Output is correct
61	Correct	6 ms	12044 KB	Output is correct
62	Correct	7 ms	12036 KB	Output is correct
63	Correct	290 ms	33528 KB	Output is correct
64	Correct	9 ms	12416 KB	Output is correct
65	Correct	16 ms	13908 KB	Output is correct
66	Correct	125 ms	26812 KB	Output is correct
67	Correct	466 ms	65396 KB	Output is correct
68	Correct	472 ms	56024 KB	Output is correct
69	Correct	13 ms	12832 KB	Output is correct
70	Correct	88 ms	21168 KB	Output is correct
71	Correct	330 ms	41796 KB	Output is correct
72	Correct	313 ms	40596 KB	Output is correct
73	Correct	90 ms	19012 KB	Output is correct
74	Correct	441 ms	37560 KB	Output is correct
75	Correct	32 ms	15212 KB	Output is correct
76	Correct	338 ms	41452 KB	Output is correct
77	Correct	309 ms	41596 KB	Output is correct
78	Correct	46 ms	15616 KB	Output is correct
79	Correct	422 ms	48612 KB	Output is correct
80	Correct	11 ms	12184 KB	Output is correct
81	Correct	98 ms	21176 KB	Output is correct
82	Correct	429 ms	39416 KB	Output is correct
83	Correct	447 ms	37592 KB	Output is correct
84	Correct	416 ms	37656 KB	Output is correct
85	Correct	441 ms	37656 KB	Output is correct
86	Correct	414 ms	38740 KB	Output is correct
87	Correct	400 ms	38784 KB	Output is correct

Submission #711678

Compilation message

Subtask #1 18.0 / 18.0

Subtask #2 45.0 / 45.0

Subtask #3 37.0 / 37.0

Subtask #1
18.0 / 18.0

Subtask #2
45.0 / 45.0

Subtask #3
37.0 / 37.0