Cod sursa(job #1869109)

Utilizator ClaudiuHHiticas Claudiu ClaudiuH Data 5 februarie 2017 16:33:58
Problema Santa Scor 100
Compilator cpp Status done
Runda becreative7 Marime 3.08 kb
#include <fstream>
#include <vector>
#include <cstring>
#include <stack>
#include <algorithm>

using namespace std;

const int nmax = 45004;
int op[nmax], viz[nmax], niv[nmax], l[nmax];
vector <int> v[nmax], sol, starts;
stack <int> stiva;
vector <vector <int> > comp;
int kill;

void solve(int x, int y);
void dfs (int k, int dad, int lvl);
bool backoff (int k, int k_maxi, int nod, int stop);
void what(vector <int> &g, int start, int stop);

int main()
{
    int n,m,x,y, e, q, source;
    ifstream cin ("santa.in");
    ofstream cout ("santa.out");
    cin >> n >> m;
    for (int i = 1; i <= m; i++)
    {
        cin >> x >> y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    cin >> source >> e >> q;
    op[source] = 1;
    starts.push_back(0);
    comp.push_back(starts);
    dfs(e, 0, 1);
    if (op[e] == 0)
    {
        cout << "No chance\n";
        return 0;
    }
    if (find(comp[1].begin(), comp[1].end(), q) == comp[1].end())
    {
        reverse(comp.begin() + 1, comp.end());
        reverse(starts.begin(), starts.end());
    }
    if (find(comp[1].begin(), comp[1].end(), q) == comp[1].end())
    {
        cout << "No chance\n";
        return 0;
    }
    starts[0] = q;
    starts[starts.size() - 1] = 0;
    sol.push_back(q);
    for (size_t i = 1 ; i < comp.size() && kill == 0; i++)
    what(comp[i], starts[i - 1], starts[i]);
    if (kill == 1)
    {
        cout << "No chance\n";
        return 0;
    }
    cout << sol.size() << "\n";
    for (size_t i = 0 ; i < sol.size(); i++)cout << sol[i] << " " ;
    return 0;
}

void solve(int x, int y)
{
    if (op[y] == 0)
    {
        while(stiva.top() != y)stiva.pop();
        stiva.pop();
        return;
    }
    starts.push_back(x);
    vector <int> c;
    while (stiva.top() != y)
    {
        c.push_back(stiva.top());
        stiva.pop();
    }
    stiva.pop();
    c.push_back(y);
    c.push_back(x);
    comp.push_back(c);
}
void dfs (int k, int dad, int lvl)
{
    niv[k] = l[k] = lvl;
    viz[k] = 1;
    for (size_t i = 0; i < v[k].size(); i++)
    {
        if (v[k][i] == dad)continue;
        if (viz[v[k][i]] == 0)
        {
            stiva.push(v[k][i]);
            dfs(v[k][i], k, lvl + 1);
            l[k] = min (l[k], l[v[k][i]]);
            if (op[v[k][i]] == 1)op[k] = 1;
            if (l[v[k][i]] >= niv[k])
            {
                solve (k, v[k][i]);
            }
        }
        else l[k] = min (l[k], niv[v[k][i]]);
    }
}
bool backoff (int k, int k_maxi, int nod, int stop)
{
    viz[nod] = 1;
    if (k > 1)sol.push_back(nod);
    if (k == k_maxi)
    {
        if (nod == stop || stop == 0)return true;
        viz[nod] = 0;
        sol.pop_back();
        return false;
    }
    for (size_t i = 0; i < v[nod].size(); i++)if((v[nod][i]!=stop||k==k_maxi-1)&&viz[v[nod][i]]==0&&backoff(k + 1, k_maxi, v[nod][i], stop) == true)return true;
    viz[nod] = 0;
    sol.pop_back();
    return false;
}

void what(vector <int> &g, int start, int stop)
{
    for (size_t i = 0 ; i < g.size(); i++)
    {
        viz[g[i]] = 0;
    }
    if (backoff(1, g.size(), start, stop) == false)
    {
        kill = 1;
    }
}