Submission #317519

#	Time	Username	Problem	Language	Result	Execution time	Memory
317519		mohamedsobhi777	Parachute rings (IOI12_rings)	C++14	20 / 100	4051 ms	183484 KiB

rings

#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:10000000")

using namespace std;
int N;
const int cn = 2e6;

vector<int> adj[cn];
int deg[cn];
int vis[cn];
int c;
bool bd = 1;
int del;
vector<int> vec;
vector<int> th;
int asy = 1;
int ac = 0;
int cs = 0;
map<pair<int, int>, int> mp, bad;

struct dsu
{
        int fat[cn];
        dsu()
        {
                memset(fat, 0, sizeof fat);
                for (int i = 0; i < cn; ++i)
                        fat[i] = i;
        }
        inline int find(int x) { return fat[x] = (x == fat[x] ? x : find(fat[x])); }
        inline bool same(int x, int y) { return find(x) == find(y); }
        void link(int u, int v)
        {
                u = find(u);
                v = find(v);
                if (fat[u] != v)
                        fat[u] = v;
        }
} d1;

void dfs(int x, int p)
{
        vis[x] = c;
        int ch = (p != x);

        for (auto u : adj[x])
        {
                if (u == p || del == u)
                        continue;
                if (vis[u] == c)
                        bd = 0;
                else
                        dfs(u, x), ++ch;
        }
        if (ch > 2)
                bd = 0;
}
vector<int> bigs;
vector<int> cyc;
vector<int> now;
int onc[cn];
int prv[cn];
set<int> unic;

bool check(int i)
{
        del = i;
        bool ok = 1;
        ++c;
        dsu cd;
        map<pair<int, int>, int> alr;
        for (auto u : cyc)
        {
                if (u == i)
                        continue;
                for (auto v : adj[u])
                {
                        if (v == i || alr[{u, v}] || alr[{v, u}])
                                continue;
                        if (cd.same(u, v))
                                ok = 0;
                        cd.link(u, v);
                        alr[{u, v}] = 1;
                }
        }
        return ok;
}
int k = 1e3;
int viz[cn];
int tar;
void detect(int x, int p)
{
        memset(prv, -1, sizeof prv);
        ++c;
        queue<int> qu;
        qu.push(x);
        bool add = 1;
        while (qu.size())
        {
                int a = qu.front();
                qu.pop();
                if (a == tar)
                {
                        int cur = tar;
                        while (~cur)
                        {
                                cyc.push_back(cur);
                                if (onc[cur])
                                        add = 0;
                                onc[cur]++;
                                unic.insert(cur);
                                cur = prv[cur];
                        }
                }
                vis[a] = c;
                for (auto u : adj[a])
                {
                        if (u != prv[a] && !bad[{u, a}])
                        {
                                prv[u] = a;
                                qu.push(u);
                        }
                }
        }
        cs += add;
}
int dp3 = -1;
set<int> bbarn;
set<int> cyc3 ; 

int brute()
{
        int ret = 0;
        set<int> uni;
        if (bigs.size() > 1)
                return 0;
        if (cs > 1)
                return 0;
        if (bigs.size())
        {
                int cnt = 0;
                return cnt + 1 >= bbarn.size() && (cs == 0 || onc[bigs[0]]) && bigs.size() == 1;
        }

        if (th.size() > 2)
        {
                int a = th[0];
                int b = th[1];
                int c = th[2];
                if (th.size() == 3 && !cs)
                {

                        assert(a != b && a != c && b != c);
                        int cnt = 0;
                        if (mp[{a, b}] && mp[{a, c}] && (cs == 0 || onc[a]))
                                ++cnt;
                        if (mp[{b, a}] && mp[{b, c}] && (cs == 0 || onc[b]))
                                ++cnt;
                        if (mp[{c, a}] && mp[{c, b}] && (cs == 0 || onc[c]))
                                ++cnt;
                        return cnt;
                }
                else if (th.size() == 3 && cs)
                {
                        int cnt = mp[{a, b}] + mp[{b, c}] + mp[{a, c}];
                        if (~dp3)
                                return dp3;
                        for (auto u : th)
                        {
                                int cn = 0;
                                for (auto j : th)
                                        if (j != u)
                                                cn += mp[{j, u}];
                                if (onc[u])
                                        if (cn == 2 && check(u))
                                        {
                                                ++ret;

                                                //  assert(onc[u] && cnt == 3);
                                        }
                                        else
                                        {
                                        }
                        }
                        return dp3 = ret;
                }
                else if (th.size() > 3)
                        return 0;
        }

        if (th.size() == 0 && cs == 0)
                return N;
        if (cs == 1 && th.size() == 0)
        {
                return (int)unic.size();
        }

        int ans1 = 0;
        if (th.size() == 1)
        {
                if (asy)
                        return 1 + (int)adj[*th.begin()].size();
                ++c;
                int a = *th.begin();
                if (cs == 1)
                {
                        ans1 = onc[a];
                        for (auto u : adj[a])
                                ans1 += onc[u];
                        return ans1;
                }
        }
        else if (th.size() == 2)
        {
                int a = th[0];
                int b = th[1];
                if (cs)
                {
                        if (onc[a] + onc[b] == 0)
                                return 0;
                }
                unordered_map<int, int> mp;
                for (auto u : adj[a])
                        mp[u]++;
                for (auto u : adj[b])
                        mp[u]++;
                mp[a]++;
                mp[b]++;
                for (auto u : mp)
                {
                        if ((onc[u.first] || !cs) && u.second == 2)
                                ++ret;
                }
                return ret;
        }
        return 0;
}

void Init(int N_)
{

        N = N_;
}
void Link(int A, int B)
{
        mp[{A, B}] = mp[{B, A}] = 1;

        if (d1.same(A, B))
        {
                ++c;
                ++ac;
                tar = B;
                detect(A, A);
                asy = 0;
                bad[{A, B}] = bad[{B, A}] = 1;
        }
        adj[A].push_back(B);
        adj[B].push_back(A);

        d1.link(A, B);
        deg[A]++;
        deg[B]++;
        if (deg[A] == 4)
        {
                bigs.push_back(A);
                for (auto u : adj[A])
                {
                        if (deg[u] > 2)
                                bbarn.insert(u);
                }
        }
        if (deg[B] == 4)
        {
                bigs.push_back(B);
                for (auto u : adj[B])
                {
                        if (deg[u] > 2)
                                bbarn.insert(u);
                }
        }
        if (deg[A] == 3)
        {
                th.push_back(A);
                if (bigs.size() && mp[{A, bigs[0]}])
                {
                        bbarn.insert(A);
                }
        }
        if (deg[B] == 3)
        {
                th.push_back(B);
                if (bigs.size() && mp[{B, bigs[0]}])
                {
                        bbarn.insert(B);
                }
        }
}

int CountCritical()
{
        if (bigs.size() > 1)
                return 0;
        return brute();
        return N;
}

Compilation message (stderr)

rings.cpp:2: warning: ignoring #pragma comment  [-Wunknown-pragmas]
    2 | #pragma comment(linker, "/STACK:10000000")
      | 
rings.cpp: In function 'int brute()':
rings.cpp:142:32: warning: comparison of integer expressions of different signedness: 'int' and 'std::set<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  142 |                 return cnt + 1 >= bbarn.size() && (cs == 0 || onc[bigs[0]]) && bigs.size() == 1;
      |                        ~~~~~~~~^~~~~~~~~~~~~~~
rings.cpp:174:36: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
  174 |                                 if (onc[u])
      |                                    ^
rings.cpp:165:29: warning: unused variable 'cnt' [-Wunused-variable]
  165 |                         int cnt = mp[{a, b}] + mp[{b, c}] + mp[{a, c}];
      |                             ^~~

• Subtask 1: 20 / 20
• Subtask 2: 0 / 17
• Subtask 3: 0 / 18
• Subtask 4: 0 / 14
• Subtask 5: 0 / 31