Submission #397846

#	Time	Username	Problem	Language	Result	Execution time	Memory
397846		maomao90	Roadside Advertisements (NOI17_roadsideadverts)	C++14	70 / 100	1087 ms	12116 KiB

roadsideadverts

#include <cstdio>
#include <vector>
#include <cstring>
#include <utility>
#include <algorithm>
#include <set>
#include <tuple>

using namespace std;

typedef pair <int, int> ii;
typedef tuple <int, int, int> iii;

#define INF 1000000005

//#define DEBUG

class UnionFind
{
private:
    vector <int> p, ranks;
public:
    void initialise(int n)
    {
        p.assign(n, 0); ranks.assign(n, 1);
        for (int i = 0; i < n; i++) p[i] = i;
    }
    int findSet(int a)
    {
        if (p[a] == a) return a;
        return p[a] = findSet(p[a]);
    }
    bool isSameSet(int a, int b)
    {
        return findSet(a) == findSet(b);
    }
    void unionSet(int a, int b)
    {
        if (!isSameSet(a, b))
        {
            int pa = findSet(a), pb = findSet(b);
            if (ranks[pa] < ranks[pb]) p[pa] = pb;
            else
            {
                p[pb] = pa;
                if (ranks[pa] == ranks[pb])
                {
                    ranks[pa]++;
                }
            }
        }
    }
};

int V, Q;
vector <ii> adjList[50005];
int sponsors[5];
bool isSponsor[50005];
int level[50005];
int dist[50005];
int p[20][50005];

int adjMatrix[50][50];
vector <iii> edgeList;
set <int> processing;
vector <int> vertices;
UnionFind UF;
int ans;

int LCA(int a, int b)
{
	if (level[a] < level[b]) swap(a, b);
	for (int i = 19; i >= 0; i--)
	{
		if (level[p[i][a]] >= level[b] && p[i][a] != -1)
		{
			a = p[i][a];
		}
	}

	if (a == b) return a;

	for (int i = 19; i >= 0; i--)
	{
		if (p[i][a] != p[i][b])
		{
			a = p[i][a]; b = p[i][b];
		}
	}
	return p[0][a];
}

void root(int source, int prevDist, int prevLvl, int prevP)
{
	dist[source] = prevDist;
	p[0][source] = prevP;
	level[source] = prevLvl;
	for (ii neighbour : adjList[source])
	{
		if (neighbour.first != prevP)
		{
			root(neighbour.first, prevDist + neighbour.second, prevLvl + 1, source);
		}
	}
}

int main()
{
	scanf("%d", &V);
	for (int i = 0; i < V-1; i++)
	{
		int u, v, w;
		scanf("%d%d%d", &u, &v, &w);
		adjList[u].emplace_back(v, w);
		adjList[v].emplace_back(u, w);
	}
	memset(p, -1, sizeof(p));
	root(0, 0, 0, -1);

	for (int k = 1; k < 20; k++)
	{
		for (int i = 0; i < V; i++)
		{
			if (p[k-1][i] != -1)
			{
				p[k][i] = p[k-1][p[k-1][i]];
			}
			else p[k][i] = -1;
		}
	}

	#ifdef DEBUG
	printf("Parent:\n");
	for (int i = 0; i < 20; i++)
    {
        printf("k=%d:", i);
        for (int j = 0; j < V; j++)
        {
            printf(" %d", p[i][j]);
        }
        printf("\n");
    }
    printf("\n");
	#endif // DEBUG

	scanf("%d", &Q);
	for (int i = 0; i < Q; i++)
	{
		memset(isSponsor, false, sizeof(isSponsor));
		for (int j = 0; j < 5; j++)
		{
			scanf("%d", sponsors + j);
			isSponsor[sponsors[j]] = true;
		}

		edgeList.clear();
		processing.clear();
		vertices.clear();
//		for (int j = 0; j < 30; j++) for (int k = 0; k < 30; k++) {
//			adjMatrix[j][k] = INF;
//		}
		for (int j = 0; j < 5; j++)
		{
			int cnt = 0;
			for (int k = j + 1; k < 5; k++)
			{
			    int temp = LCA(sponsors[j], sponsors[k]);
				processing.insert(temp);
				// adjMatrix[sponsors[j]][temp] = adjMatrix[temp][sponsors[j]] = dist[sponsors[j]] - dist[temp];
				// adjMatrix[k][temp] = adjMatrix[temp][k] = dist[k] - dist[temp];
			    // edgeList.emplace_back(dist[sponsors[j]] - dist[temp], sponsors[j], temp);
			    // edgeList.emplace_back(dist[k] - dist[temp], k, temp);
			}
			processing.insert(sponsors[j]);
		}

		for (auto &i : processing) vertices.push_back(i);
		for (int j = 0; j < vertices.size(); j++) {
			for (int k = j + 1; k < vertices.size(); k++) {
				int tempj = vertices[j], tempk = vertices[k];
				int lca = LCA(tempj, tempk);
				edgeList.emplace_back(dist[tempj] + dist[tempk] - 2 * dist[lca], tempj, tempk);
			}
		}
//		for (int l = 0; l < 30; l++) for (int j = 0; j < 30; j++) for (int k = 0; k < 30; k++) {
//			adjMatrix[j][k] = min(adjMatrix[j][k], adjMatrix[j][l] + adjMatrix[l][k]);
//		}
//		for (int j = 0; j < 30; j++) for (int k = 0; k < 30; k++) {
//			if (adjMatrix[j][k] != INF) {
//				edgeList.emplace_back(adjMatrix[j][k], j, k);
//			}
//		}
		sort(edgeList.begin(), edgeList.end());

		ans = 0;
		UF.initialise(V+5);
		for (int j = 0; j < edgeList.size(); j++)
		{
		    int u, v, w; tie(w, u, v) = edgeList[j];
		    if (!UF.isSameSet(u, v))
            {
                ans += w;
                UF.unionSet(u, v);
            }
		}
		printf("%d\n", ans);
	}
	return 0;
}

/*
6
4 0 4
0 1 2
1 3 9
3 5 1
3 2 5
2
4 0 3 5 2
0 4 1 3 5
*/

Compilation message (stderr)

roadsideadverts.cpp: In function 'int main()':
roadsideadverts.cpp:164:8: warning: unused variable 'cnt' [-Wunused-variable]
  164 |    int cnt = 0;
      |        ^~~
roadsideadverts.cpp:178:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  178 |   for (int j = 0; j < vertices.size(); j++) {
      |                   ~~^~~~~~~~~~~~~~~~~
roadsideadverts.cpp:179:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  179 |    for (int k = j + 1; k < vertices.size(); k++) {
      |                        ~~^~~~~~~~~~~~~~~~~
roadsideadverts.cpp:197:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::tuple<int, int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  197 |   for (int j = 0; j < edgeList.size(); j++)
      |                   ~~^~~~~~~~~~~~~~~~~
roadsideadverts.cpp:109:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  109 |  scanf("%d", &V);
      |  ~~~~~^~~~~~~~~~
roadsideadverts.cpp:113:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  113 |   scanf("%d%d%d", &u, &v, &w);
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~~~
roadsideadverts.cpp:146:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  146 |  scanf("%d", &Q);
      |  ~~~~~^~~~~~~~~~
roadsideadverts.cpp:152:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  152 |    scanf("%d", sponsors + j);
      |    ~~~~~^~~~~~~~~~~~~~~~~~~~

• Subtask 1: 7 / 7
• Subtask 2: 23 / 23
• Subtask 3: 40 / 40
• Subtask 4: 0 / 30