제출 #127096

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
127096		Lawliet	Mousetrap (CEOI17_mousetrap)	C++14	25 / 100	1291 ms	72668 KiB

mousetrap

#include <bits/stdc++.h>
 
#define MAX 1000010
 
using namespace std;
typedef long long int lli;
 
int n;
int mouse, trap;
int n1, n2;
 
int pai[MAX];
 
lli dp[MAX];
 
vector<int> grafo[MAX];
 
void DFSInit(int i, int p)
{
	for(int g = 0 ; g < grafo[i].size() ; g++)
	{
		int prox = grafo[i][g];
 
		if(prox == p) continue;
 
		pai[prox] = i;
 
		DFSInit(prox , i);
	}
}
 
void DFS(int i)
{
	if(grafo[i].size() == 1 && i != trap)
	{
		dp[i] = 0;
 
		return;
	}
 
	vector<lli> aux;
 
	aux.push_back( 0 );
 
	for(int g = 0 ; g < grafo[i].size() ; g++)
	{
		int prox = grafo[i][g];
 
		if(prox == pai[i]) continue;
 
		//printf("i = %d   chamei %d\n",i,prox);
 
		//printf("i = %d  prox = %d\n",i,prox);
 
		DFS(prox);
 
		aux.push_back( dp[prox] );
	}
 
	sort(aux.begin() , aux.end());
 
	dp[i] = grafo[i].size() - 2 + aux[aux.size() - 2] + 1;
 
	//printf("dp(%d) = %lld\n",i,dp[i]);
}
 
int main()
{
	scanf("%d %d %d",&n,&trap,&mouse);
 
	for(int g = 0 ; g < n - 1 ; g++)
	{
		scanf("%d %d",&n1,&n2);
 
		grafo[n1].push_back(n2);
		grafo[n2].push_back(n1);
	}
 
	if(trap == mouse)
	{
		printf("0\n");
		return 0;
	}

	DFSInit(trap , trap);
 
	lli ans = -1;
	int cur = mouse;
 
	while(cur != trap)
	{
		//printf("\n\n\n\n");
		DFS(trap);
 
		//printf("cur = %d\n",cur);
 
		int aux = pai[cur];
		int sum = 0;
 
		while(aux != trap)
		{
			sum += grafo[aux].size() - 2;
			aux = pai[aux];
		}
 
		//printf("dp = %d  sum = %d\n",dp[cur],sum);
 
		ans = max(ans , dp[cur] + sum);
 
		for(int g = 0 ; g < grafo[pai[cur]].size() ; g++)
		{
			int prox = grafo[pai[cur]][g];
 
			if(prox == cur)
			{
				grafo[pai[cur]].erase(grafo[pai[cur]].begin() + g);
				break;
			}
		}
 
		cur = pai[cur];
	}
 
	printf("%lld\n",ans);
}

컴파일 시 표준 에러 (stderr) 메시지

mousetrap.cpp: In function 'void DFSInit(int, int)':
mousetrap.cpp:20:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int g = 0 ; g < grafo[i].size() ; g++)
                  ~~^~~~~~~~~~~~~~~~~
mousetrap.cpp: In function 'void DFS(int)':
mousetrap.cpp:45:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int g = 0 ; g < grafo[i].size() ; g++)
                  ~~^~~~~~~~~~~~~~~~~
mousetrap.cpp: In function 'int main()':
mousetrap.cpp:110:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int g = 0 ; g < grafo[pai[cur]].size() ; g++)
                   ~~^~~~~~~~~~~~~~~~~~~~~~~~
mousetrap.cpp:69:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d %d",&n,&trap,&mouse);
  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
mousetrap.cpp:73:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d",&n1,&n2);
   ~~~~~^~~~~~~~~~~~~~~~~

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