Submission #799321

#	Time	Username	Problem	Language	Result	Execution time	Memory
799321		jlallas384	Parachute rings (IOI12_rings)	C++17	37 / 100	1786 ms	198716 KiB

rings

#include <bits/stdc++.h>
using namespace std;
 
 
 
struct ufds{
    vector<int> sz, par;
    ufds(){}
    ufds(int n): sz(n, 1), par(n){
        iota(par.begin(), par.end(), 0);
    }
    int find(int a){
        return par[a] == a ? a : par[a] = find(par[a]);
    }
    int unite(int a, int b){
        a = find(a), b = find(b);
        if(a == b) return 0;
        if(sz[a] < sz[b]) swap(a, b);
        par[b] = a;
        sz[a] += sz[b];
        return 1;
    }
};
 
set<int> ans;
vector<vector<int>> g, tree;
vector<int> deg;
int n;
ufds ds;
 
int bad = 0;
int d4 = 0;
 
void Init(int N){
    n = N;
    g.resize(n);
    tree.resize(n);
    deg.resize(n);
    for(int i = 0; i < n; i++){
        ans.insert(i);
    }
    ds = ufds(n);
}
 
void proc(int a, int add = 1){
    if(deg[a] == 4){
        if(add){
            d4++;
            if(d4 == 2) bad = 1;
        }
        if(!ans.count(a)) ans = {};
        else ans = {a};
    }else if(deg[a] == 3){
        set<int> nans;
        if(ans.count(a)) nans.insert(a);
        for(int u: g[a]){
            if(ans.count(u)) nans.insert(u);
        }
        ans = nans;
    }
}

int dfs4(int v, int p, vector<int> &vis){
    vis[v] = 2;
    for(int u: g[v]){
        if(!vis[u] && dfs4(u, v, vis)) return 1;
        else if(vis[u] == 2 && u != p){
            return 1;
        }
    }
    return 0;
}
int cyc = 0;
int CountCritical(){    

    if(bad) return 0;
    else{
        for(int x: ans) if(deg[x] > 2){
            vector<int> vis(n);
            vis[x] = 1;
            for(int i = 0; i < n; i++) if(vis[i] == 0 && cyc){
                assert(!dfs4(i, -1, vis));
            }
        }
        return ans.size();
    }
}
 
 
 

vector<int> path;
int dfs(int v, int p, int x){
    path.push_back(v);
    if(v == x) return 1;
    for(int u: tree[v]) if(u != p){
        if(dfs(u, v, x)) return 1;
    }
    path.pop_back();
    return 0;
}
 
void dfs2(int v, set<int> &vis){
    if(ans.count(v)) return;
    vis.insert(v);
    for(int u: g[v]) if(!vis.count(u)){
        dfs2(u, vis);
    }
}
 
int dfs3(int v, set<int> &v1, set<int> &v2){
    if(ans.count(v)) return 0;
    if(v1.count(v)) return 1;
    v2.insert(v);
    for(int u: g[v]) if(!v2.count(u)){
        if(dfs3(u, v1, v2)) return 1;
    }
    return 0;
}



void Link(int a, int b){
    if(bad) return;
    int res = ds.unite(a, b);
    deg[a]++, deg[b]++;
    g[a].push_back(b);
    g[b].push_back(a);
    proc(a), proc(b);
    if(!res){
        if(!cyc){
            dfs(a, -1, b);
            ans = {};
            for(int x: path){
                ans.insert(x);
            }
            for(int i = 0; i < n; i++){
                proc(i, 0);
            }
            cyc = 1;
        }else{
            if(ans.size() >= 3) bad = 1;
            g[a].pop_back();
            g[b].pop_back();
            set<int> v1, v2;
            dfs2(a, v1);
            if(dfs3(b, v1, v2)){
                bad = 1;
            }
            g[a].push_back(b);
            g[b].push_back(a);
        }
    }else{
        tree[a].push_back(b);
        tree[b].push_back(a);

    }
}

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