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Submission #288743

# Submission time Handle Problem Language Result Execution time Memory
288743 2020-09-01T20:30:23 Z TadijaSebez Mousetrap (CEOI17_mousetrap) C++11
100 / 100
 1080 ms 202616 KB 
#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define pii pair<int,int>
const int N=1000050;
vector<int> E[N];
int dp[N],dep[N],n,t,m;
bool on[N];
void DP(int u,int p){
	vector<int> d;
	for(int v:E[u])if(v!=p){
		if(p)dp[v]=dp[u]+E[u].size()-2;
		DP(v,u);
		if(on[v])on[u]=1;
		d.pb(dp[v]);
	}
	sort(d.rbegin(),d.rend());
	if(d.size()>1)dp[u]=d[1];
	dp[u]+=E[u].size()>1;
}
vector<pii> tmp;
void DFS(int u,int p){
	if(u==t)return;
	for(int v:E[u])if(v!=p){
		dep[v]=dep[u]+1;
		if(on[u]&&!on[v])tmp.pb({dep[v],dp[v]+(u==m)});
		else DFS(v,u);
	}
}
bool Check(int mid){
	int need=0;
	for(auto p:tmp){
		if(need>p.first)return 0;
		if(p.second+need>mid)need++;
	}
	return need<=mid;
}
int main(){
	scanf("%i %i %i",&n,&t,&m);
	for(int i=1,u,v;i<n;i++)scanf("%i %i",&u,&v),E[u].pb(v),E[v].pb(u);
	on[m]=1;dep[m]=-1;
	DP(t,0);
	DFS(m,0);
	sort(tmp.begin(),tmp.end());
	int top=n,bot=0,mid,ans;
	while(top>=bot){
		mid=top+bot>>1;
		if(Check(mid))ans=mid,top=mid-1;
		else bot=mid+1;
	}
	printf("%i\n",ans);
	return 0;
}

Compilation message

mousetrap.cpp: In function 'int main()':
mousetrap.cpp:47:10: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   47 |   mid=top+bot>>1;
      |       ~~~^~~~
mousetrap.cpp:39:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   39 |  scanf("%i %i %i",&n,&t,&m);
      |  ~~~~~^~~~~~~~~~~~~~~~~~~~~
mousetrap.cpp:40:31: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   40 |  for(int i=1,u,v;i<n;i++)scanf("%i %i",&u,&v),E[u].pb(v),E[v].pb(u);
      |                          ~~~~~^~~~~~~~~~~~~~~

Subtask #1
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 23808 KB Output is correct
2 Correct 14 ms 23808 KB Output is correct
3 Correct 14 ms 23808 KB Output is correct
4 Correct 14 ms 23808 KB Output is correct
5 Correct 14 ms 23808 KB Output is correct
6 Correct 14 ms 23808 KB Output is correct
7 Correct 13 ms 23808 KB Output is correct
8 Correct 14 ms 23808 KB Output is correct
9 Correct 14 ms 23808 KB Output is correct
10 Correct 14 ms 23808 KB Output is correct

Subtask #2
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 457 ms 72344 KB Output is correct
2 Correct 415 ms 67576 KB Output is correct
3 Correct 970 ms 73572 KB Output is correct
4 Correct 448 ms 48448 KB Output is correct
5 Correct 991 ms 73448 KB Output is correct
6 Correct 998 ms 73464 KB Output is correct

Subtask #3
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 23808 KB Output is correct
2 Correct 14 ms 23808 KB Output is correct
3 Correct 14 ms 23808 KB Output is correct
4 Correct 14 ms 23808 KB Output is correct
5 Correct 14 ms 23808 KB Output is correct
6 Correct 14 ms 23808 KB Output is correct
7 Correct 13 ms 23808 KB Output is correct
8 Correct 14 ms 23808 KB Output is correct
9 Correct 14 ms 23808 KB Output is correct
10 Correct 14 ms 23808 KB Output is correct
11 Correct 15 ms 23808 KB Output is correct
12 Correct 15 ms 23808 KB Output is correct
13 Correct 16 ms 23808 KB Output is correct
14 Correct 16 ms 23936 KB Output is correct
15 Correct 17 ms 23936 KB Output is correct
16 Correct 15 ms 23808 KB Output is correct
17 Correct 16 ms 23808 KB Output is correct
18 Correct 15 ms 23936 KB Output is correct
19 Correct 15 ms 23936 KB Output is correct
20 Correct 15 ms 23936 KB Output is correct
21 Correct 15 ms 23936 KB Output is correct
22 Correct 15 ms 23808 KB Output is correct

Subtask #4
35.0 / 35.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 23808 KB Output is correct
2 Correct 14 ms 23808 KB Output is correct
3 Correct 14 ms 23808 KB Output is correct
4 Correct 14 ms 23808 KB Output is correct
5 Correct 14 ms 23808 KB Output is correct
6 Correct 14 ms 23808 KB Output is correct
7 Correct 13 ms 23808 KB Output is correct
8 Correct 14 ms 23808 KB Output is correct
9 Correct 14 ms 23808 KB Output is correct
10 Correct 14 ms 23808 KB Output is correct
11 Correct 457 ms 72344 KB Output is correct
12 Correct 415 ms 67576 KB Output is correct
13 Correct 970 ms 73572 KB Output is correct
14 Correct 448 ms 48448 KB Output is correct
15 Correct 991 ms 73448 KB Output is correct
16 Correct 998 ms 73464 KB Output is correct
17 Correct 15 ms 23808 KB Output is correct
18 Correct 15 ms 23808 KB Output is correct
19 Correct 16 ms 23808 KB Output is correct
20 Correct 16 ms 23936 KB Output is correct
21 Correct 17 ms 23936 KB Output is correct
22 Correct 15 ms 23808 KB Output is correct
23 Correct 16 ms 23808 KB Output is correct
24 Correct 15 ms 23936 KB Output is correct
25 Correct 15 ms 23936 KB Output is correct
26 Correct 15 ms 23936 KB Output is correct
27 Correct 15 ms 23936 KB Output is correct
28 Correct 15 ms 23808 KB Output is correct
29 Correct 17 ms 23840 KB Output is correct
30 Correct 487 ms 72392 KB Output is correct
31 Correct 459 ms 72540 KB Output is correct
32 Correct 564 ms 202616 KB Output is correct
33 Correct 537 ms 197944 KB Output is correct
34 Correct 1026 ms 73720 KB Output is correct
35 Correct 1025 ms 73732 KB Output is correct
36 Correct 1052 ms 91992 KB Output is correct
37 Correct 1080 ms 91928 KB Output is correct
38 Correct 854 ms 90672 KB Output is correct
39 Correct 851 ms 90736 KB Output is correct
40 Correct 866 ms 90740 KB Output is correct