Submission #210681

#	Time	Username	Problem	Language	Result	Execution time	Memory
210681		peuch	Dreaming (IOI13_dreaming)	C++17	47 / 100	229 ms	20216 KiB

dreaming

#include<bits/stdc++.h>
#include "dreaming.h"
using namespace std;

const int MAXN = 1e5 + 10; 

int marc[MAXN], dist[MAXN], longDist[2][MAXN];
int aux;

vector<int> ar[MAXN];
vector<int> wg[MAXN];
vector<pair<int, int> > group;

int dfs1(int cur);
int dfs2(int cur);
pair<int, int> dfs3(int cur);

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
	for(int i = 0; i < M; i++){
		ar[A[i]].push_back(B[i]);
		ar[B[i]].push_back(A[i]);
		wg[A[i]].push_back(T[i]);
		wg[B[i]].push_back(T[i]);
	}
	int ret = 0;
	for(int i = 0; i < N; i++){
		if(marc[i] == 3) continue;
		dist[i] = 0;
		aux = 0;
		int side1 = dfs1(i);
		longDist[0][side1] = 0;
		int side2 = dfs2(side1);
		// ret = max(ret, longDist[0][side2]);
		// printf("group: %d ends = %d and %d with %d nodes\n", group.size(), side1, side2, aux);
		longDist[1][side2] = 0;
		group.push_back(dfs3(side2));
	}	
	// printf("%d\n", group.size());
	// for(int i = 0; i < group.size(); i++)
	// 	printf("%d ", group[i]);
	// printf("\n");
	for(int i = 1; i < group.size(); i++){
		ar[group[i].second].push_back(group[i - 1].second);
		ar[group[i - 1].second].push_back(group[i].second);
		wg[group[i].second].push_back(L);
		wg[group[i - 1].second].push_back(L);
		if(max(group[i].first, group[i - 1].first + L) < max(group[i - 1].first, group[i].first + L)){
			group[i].first = max(group[i].first, group[i - 1].first + L);
			group[i].second = group[i].first;
		}
		else{
			group[i].first = max(group[i - 1].first, group[i].first + L);
			group[i].second = group[i - 1].first;
		}
	}
	int side1 = dfs1(0);
	longDist[0][side1] = 0;
	int side2 = dfs2(side1);
	// ret = max(ret, longDist[0][side2]);
	// printf("group: %d ends = %d and %d with %d nodes\n", group.size(), side1, side2, aux);
    return longDist[0][side2];
}

int dfs1(int cur){
	marc[cur] = 1;
	aux++;
	int ret = cur;
	int auxRet = dist[cur];
	for(int i = 0; i < ar[cur].size(); i++){
		int viz = ar[cur][i];
		int len = wg[cur][i];
		if(marc[viz] == 1) continue;
		dist[viz] = dist[cur] + len;
		int dfsVal = dfs1(viz);
		if(dist[dfsVal] > auxRet) ret = dfsVal, auxRet = dist[dfsVal];
 	} 
 	return ret;
}

int dfs2(int cur){
	marc[cur] = 2;
	int ret = cur;
	int auxRet = longDist[0][cur];
	for(int i = 0; i < ar[cur].size(); i++){
		int viz = ar[cur][i];
		int len = wg[cur][i];
		if(marc[viz] == 2) continue;
		longDist[0][viz] = longDist[0][cur] + len;
		int dfsVal = dfs2(viz);
		if(longDist[0][dfsVal] > auxRet) ret = dfsVal, auxRet = longDist[0][dfsVal];
 	} 
 	return ret;
}

pair<int, int> dfs3(int cur){
	marc[cur] = 3;
	int ret = cur;
	int auxRet = max(longDist[0][cur], longDist[1][cur]);
	for(int i = 0; i < ar[cur].size(); i++){
		int viz = ar[cur][i];
		int len = wg[cur][i];
		if(marc[viz] == 3) continue;
		longDist[1][viz] = longDist[1][cur] + len;
		pair<int, int> dfsVal = dfs3(viz);
		if(dfsVal.first < auxRet) ret = dfsVal.second, auxRet = dfsVal.first;
 	} 
 	// printf("%d max(%d %d) -> %d\n", cur, longDist[0][cur], longDist[1][cur], ret);
 	return make_pair(auxRet, ret);
}

Compilation message (stderr)

dreaming.cpp: In function 'int travelTime(int, int, int, int*, int*, int*)':
dreaming.cpp:42:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 1; i < group.size(); i++){
                 ~~^~~~~~~~~~~~~~
dreaming.cpp:25:6: warning: unused variable 'ret' [-Wunused-variable]
  int ret = 0;
      ^~~
dreaming.cpp: In function 'int dfs1(int)':
dreaming.cpp:69:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 0; i < ar[cur].size(); i++){
                 ~~^~~~~~~~~~~~~~~~
dreaming.cpp: In function 'int dfs2(int)':
dreaming.cpp:84:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 0; i < ar[cur].size(); i++){
                 ~~^~~~~~~~~~~~~~~~
dreaming.cpp: In function 'std::pair<int, int> dfs3(int)':
dreaming.cpp:99:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 0; i < ar[cur].size(); i++){
                 ~~^~~~~~~~~~~~~~~~

• Subtask 1: 14 / 14
• Subtask 2: 10 / 10
• Subtask 3: 23 / 23
• Subtask 4: 0 / 18
• Subtask 5: 0 / 12
• Subtask 6: 0 / 23