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Submission #161608

# Submission time Handle Problem Language Result Execution time Memory
161608 2019-11-03T09:26:53 Z shayan_p Mousetrap (CEOI17_mousetrap) C++14
100 / 100
 1123 ms 198952 KB 
// Remember...

#include<bits/stdc++.h>

#define F first
#define S second
#define PB push_back
#define sz(s) int((s).size())
#define bit(n,k) (((n)>>(k))&1)

using namespace std;

typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

const int maxn=1e6+10,mod=1e9+7;
const ll inf=1e18;

vector<int> v[maxn], dps[maxn], path;
int dp[maxn], pr[maxn];

bool mark[maxn];

void dfs(int u,int par){
    pr[u]=par;
    int id=-1, cnt=0;
    for(int y:v[u]){
	if(y!=par){
	    cnt++;
	    dfs(y,u);
	    if(id==-1 || dp[id]<dp[y])
		id=y;
	}
    }
    for(int y:v[u]){
	if(y!=par && y!=id)
	    dp[u]=max(dp[u], dp[y]);
    }
    dp[u]+=cnt;
}

bool ok(int lm){
    int tot=0, usd=0;
    for(int i=0;i<sz(path);i++){
	tot+=sz(dps[i]);
    }
    for(int i=0;i<sz(path);i++){
	usd++;
	int pt=0, cnt=0;
	while(pt<sz(dps[i]) && dps[i][pt]+tot>lm)
	    usd--, pt++, cnt++;
	lm-=cnt;
	tot-=sz(dps[i]);
	if(usd<0 || lm<0) return 0;
    }
    return 1;
}

int main(){
    ios_base::sync_with_stdio(false); cin.tie(0); cout.tie();

    int n,t,m; cin>>n>>t>>m;
    for(int i=0;i<n-1;i++){
	int a,b; cin>>a>>b;
	v[a].PB(b);
	v[b].PB(a);
    }
    dfs(t,-1);
    
    int tmp=m;
    while(tmp!=t){
	mark[tmp]=1;
	path.PB(tmp);
	tmp=pr[tmp];
    }
    mark[t]=1;

    for(int i=0;i<sz(path);i++){
	for(int u:v[path[i]]){
	    if(mark[u]==0)
		dps[i].PB(dp[u]);
	}
	sort(dps[i].begin(),dps[i].end(),greater<int>());
    }
    int l=-1,r=n-1;
    while(r-l>1){
	int mid=(l+r)>>1;
	if(ok(mid)) r=mid;
	else l=mid;
    }    
    return cout<<r<<endl,0;
}
// Deathly mistakes:
//  * Read the problem carefully.
//  * Check maxn.
//  * Overflows.


// #pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")

Subtask #1
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 48 ms 47352 KB Output is correct
2 Correct 47 ms 47352 KB Output is correct
3 Correct 47 ms 47352 KB Output is correct
4 Correct 46 ms 47340 KB Output is correct
5 Correct 52 ms 47352 KB Output is correct
6 Correct 50 ms 47352 KB Output is correct
7 Correct 46 ms 47352 KB Output is correct
8 Correct 50 ms 47276 KB Output is correct
9 Correct 47 ms 47292 KB Output is correct
10 Correct 47 ms 47352 KB Output is correct

Subtask #2
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 451 ms 86516 KB Output is correct
2 Correct 416 ms 82728 KB Output is correct
3 Correct 991 ms 87656 KB Output is correct
4 Correct 478 ms 67552 KB Output is correct
5 Correct 1008 ms 87772 KB Output is correct
6 Correct 1123 ms 87624 KB Output is correct

Subtask #3
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 48 ms 47352 KB Output is correct
2 Correct 47 ms 47352 KB Output is correct
3 Correct 47 ms 47352 KB Output is correct
4 Correct 46 ms 47340 KB Output is correct
5 Correct 52 ms 47352 KB Output is correct
6 Correct 50 ms 47352 KB Output is correct
7 Correct 46 ms 47352 KB Output is correct
8 Correct 50 ms 47276 KB Output is correct
9 Correct 47 ms 47292 KB Output is correct
10 Correct 47 ms 47352 KB Output is correct
11 Correct 47 ms 47312 KB Output is correct
12 Correct 47 ms 47420 KB Output is correct
13 Correct 47 ms 47352 KB Output is correct
14 Correct 49 ms 47452 KB Output is correct
15 Correct 46 ms 47480 KB Output is correct
16 Correct 47 ms 47480 KB Output is correct
17 Correct 46 ms 47352 KB Output is correct
18 Correct 47 ms 47352 KB Output is correct
19 Correct 50 ms 47224 KB Output is correct
20 Correct 48 ms 47352 KB Output is correct
21 Correct 49 ms 47360 KB Output is correct
22 Correct 47 ms 47352 KB Output is correct

Subtask #4
35.0 / 35.0

# Verdict Execution time Memory Grader output
1 Correct 48 ms 47352 KB Output is correct
2 Correct 47 ms 47352 KB Output is correct
3 Correct 47 ms 47352 KB Output is correct
4 Correct 46 ms 47340 KB Output is correct
5 Correct 52 ms 47352 KB Output is correct
6 Correct 50 ms 47352 KB Output is correct
7 Correct 46 ms 47352 KB Output is correct
8 Correct 50 ms 47276 KB Output is correct
9 Correct 47 ms 47292 KB Output is correct
10 Correct 47 ms 47352 KB Output is correct
11 Correct 451 ms 86516 KB Output is correct
12 Correct 416 ms 82728 KB Output is correct
13 Correct 991 ms 87656 KB Output is correct
14 Correct 478 ms 67552 KB Output is correct
15 Correct 1008 ms 87772 KB Output is correct
16 Correct 1123 ms 87624 KB Output is correct
17 Correct 47 ms 47312 KB Output is correct
18 Correct 47 ms 47420 KB Output is correct
19 Correct 47 ms 47352 KB Output is correct
20 Correct 49 ms 47452 KB Output is correct
21 Correct 46 ms 47480 KB Output is correct
22 Correct 47 ms 47480 KB Output is correct
23 Correct 46 ms 47352 KB Output is correct
24 Correct 47 ms 47352 KB Output is correct
25 Correct 50 ms 47224 KB Output is correct
26 Correct 48 ms 47352 KB Output is correct
27 Correct 49 ms 47360 KB Output is correct
28 Correct 47 ms 47352 KB Output is correct
29 Correct 46 ms 47324 KB Output is correct
30 Correct 454 ms 99840 KB Output is correct
31 Correct 550 ms 99976 KB Output is correct
32 Correct 719 ms 198952 KB Output is correct
33 Correct 533 ms 193948 KB Output is correct
34 Correct 988 ms 100760 KB Output is correct
35 Correct 1014 ms 100828 KB Output is correct
36 Correct 1041 ms 113692 KB Output is correct
37 Correct 1035 ms 113684 KB Output is correct
38 Correct 852 ms 115368 KB Output is correct
39 Correct 846 ms 115460 KB Output is correct
40 Correct 876 ms 115408 KB Output is correct