Submission #122974

#	Time	Username	Problem	Language	Result	Execution time	Memory
122974		davitmarg	Mousetrap (CEOI17_mousetrap)	C++17	0 / 100	79 ms	23800 KiB

mousetrap

/*DavitMarg*/
#include <iostream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <string>
#include <cstring>
#include <map>
#include <unordered_map>
#include <bitset>
#include <set>
#include <queue>
#include <deque>
#include <stack>
#include <iterator>
#include <ctype.h>
#include <stdlib.h>
#include <cassert>
#include <fstream>
#define mod 1000000007ll
#define LL long long
#define LD long double
#define MP make_pair
#define PB push_back
#define all(v) v.begin(),v.end()
using namespace std;

int n,trap,m,u[100005],nxt[100005],dp[100005],d[100005],ans;
vector<int> g[100005],t[100005];

void maketree(int v)
{
    u[v]=1;
    if(v==trap)
	{
		nxt[v]=1;
        return;
	}
    for(int i=0;i<g[v].size();i++)
	{
        int to=g[v][i];
		if(u[to])
			continue;
        t[v].PB(to);
        maketree(to);
        if(nxt[to])
		{
			dp[v]+=dp[to];
			nxt[v]=1;
		}
	}
    dp[v]+=t[v].size()-1;
    dp[v]*=nxt[v];
}

void dfs(int v,int p=0,int last=1,int sum=0)
{
    d[v]=d[p]+1;
    if(nxt[v])
	{
        last=v;
        sum=0;
	}
	else if(!t[v].empty())
		sum+=t[v].size()-1;
    for(int i=0;i<t[v].size();i++)
	{
		int to=t[v][i];
        dfs(to,v,last,sum);
	}

    if(t[v].empty() && !nxt[v])
        ans=max(ans,dp[last]+sum-1+d[v]-d[last]);
}

int main()
{
    cin>>n>>trap>>m;
    for(int i=1;i<=n-1;i++)
	{
        int a,b;
        scanf("%d%d",&a,&b);
        g[a].PB(b);
        g[b].PB(a);
	}
    maketree(m);
    d[0]=-1;
	dfs(m);
    cout<<ans<<endl;
	return 0;
}

/*

5 2 5
5 1
1 2
1 3
1 4

*/

Compilation message (stderr)

mousetrap.cpp: In function 'void maketree(int)':
mousetrap.cpp:39:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<g[v].size();i++)
                 ~^~~~~~~~~~~~
mousetrap.cpp: In function 'void dfs(int, int, int, int)':
mousetrap.cpp:66:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<t[v].size();i++)
                 ~^~~~~~~~~~~~
mousetrap.cpp: In function 'int main()':
mousetrap.cpp:82:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d",&a,&b);
         ~~~~~^~~~~~~~~~~~~~

• Subtask 1: 0 / 20
• Subtask 2: 0 / 25
• Subtask 3: 0 / 20
• Subtask 4: 0 / 35