Submission #306551

#	Time	Username	Problem	Language	Result	Execution time	Memory
306551		andreiomd	Connecting Supertrees (IOI20_supertrees)	C++14	21 / 100	265 ms	27128 KiB

supertrees

#include "supertrees.h"
#include <vector>

using namespace std;

const int NMAX = 1e3 + 1;

int N, roads[NMAX][NMAX];
bool G[NMAX][NMAX];

vector < int > roots;
vector < int > list[NMAX];

vector < vector < int > > ans;

class DSU
{
    static const int NMAX = 1e3 + 1;
    int T[NMAX], Size[NMAX];

private:
    inline int Find (int Node)
    {
        if(Node == T[Node])
            return Node;

        return (T[Node] = Find(T[Node]));
    }

    inline void my_swap (int &x, int &y)
    {
        x = (x ^ y), y = (x ^ y), x = (x ^ y);

        return;
    }

public:
    inline void Initialize (int N)
    {
        for(int i = 1; i <= N; ++i)
            T[i] = i, Size[i] = 1;

        return;
    }

    inline bool Unify (int X, int Y)
    {
        X = Find(X), Y = Find(Y);

        if(X == Y)
            return 0;

        if(Size[X] < Size[Y])
            my_swap(X, Y);

        T[Y] = X;
        Size[X] += Size[Y], Size[Y] = 0;

        return 1;
    }

    inline int Id (int Node)
    {
        return Find(Node);
    }

    inline int Sz (int Id)
    {
        return Size[Id];
    }
} trees, cycles;

static inline void Add_Edge (int X, int Y)
{
    G[X][Y] = G[Y][X] = 1;

    return;
}

static inline void Build_Trees ()
{
    trees.Initialize(N);

    for(int i = 1; i < N; ++i)
        for(int j = (i + 1); j <= N; ++j)
            if(roads[i][j] == 1)
                trees.Unify(i, j);

    for(int i = 1; i <= N; ++i)
    {
        int father = trees.Id(i);

        if(father == i)
            roots.push_back(i);
        else
            Add_Edge(i, father);
    }

    return;
}

static inline void Build_Cycles ()
{
    cycles.Initialize(N);

    for(int i = 0; i < (int)roots.size() - 1; ++i)
        for(int j = (i + 1); j < (int)roots.size(); ++j)
        {
            int X = roots[i], Y = roots[j];

            if(roads[X][Y] == 2)
                cycles.Unify(X, Y);
        }

    for(auto it : roots)
    {
        int father = cycles.Id(it), i = it;

        if(cycles.Sz(father) > 1)
            list[father].push_back(i);
    }

    return;
}

static inline void Go_to_collect_solution ()
{
    for(int i = 1; i <= N; ++i)
    {
        vector < int > line;

        for(int j = 1; j <= N; ++j)
            line.push_back(G[i][j]);

        ans.push_back(line);
    }

    return;
}

int construct (vector < vector < int > > p)
{
    N = (int)p.size();

    for(int i = 1; i <= N; ++i)
        for(int j = 1; j <= N; ++j)
        {
            roads[i][j] = p[i - 1][j - 1];

            if(roads[i][j] > 2)
                return 0;
        }

    Build_Trees();

    for(int i = 1; i < N; ++i)
        for(int j = (i + 1); j <= N; ++j)
            if(roads[i][j] == 0 && trees.Id(i) == trees.Id(j))
                return 0;

    Build_Cycles();

    for(int i = 1; i <= N; ++i)
    {
        if(list[i].empty())
            continue;

        if((int)list[i].size() == 1 || (int)list[i].size() == 2)
            return 0;

        for(int p1 = 0; p1 < (int)list[i].size() - 1; ++p1)
            for(int p2 = (p1 + 1); p2 < (int)list[i].size(); ++p2)
                if(roads[p1][p2] != 2)
                    return 0;

        for(int p1 = 0; p1 < (int)list[i].size() - 1; ++p1)
            Add_Edge(list[i][p1], list[i][p1 + 1]);

        Add_Edge(list[i][0], list[i].back());
    }

    Go_to_collect_solution(), build(ans);

    return 1;
}

• Subtask 1: 11 / 11
• Subtask 2: 10 / 10
• Subtask 3: 0 / 19
• Subtask 4: 0 / 35
• Subtask 5: 0 / 21
• Subtask 6: 0 / 4