Submission #400746

#	Time	Username	Problem	Language	Result	Execution time	Memory
400746		teehandsome	Connecting Supertrees (IOI20_supertrees)	C++17	21 / 100	284 ms	26084 KiB

supertrees

#include "supertrees.h"
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define endl '\n'
#define INF 1e9+7
#define all(x) x.begin(),x.end()
using namespace std;
using namespace __gnu_pbds;
using ll=long long;
using pii=pair<int,int>;
using ppi=pair<int,pii>;
using oset=tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update>;

template<typename T>
void _print(vector<T> x) {cerr<<"{"; for(auto e:x) cerr<<e<<","; cerr<<"}";}
void _print(pii x) {cerr<<"{"<<x.first<<","<<x.second<<"}";}
template<typename T>
void _print(T x) {cerr<<x;}

void dbg() {cerr<<endl;}
template<typename Head,typename... Tail>
void dbg(Head H,Tail... T) {
    _print(H);
    if(sizeof...(T)) cerr<<",";
    else cerr<<"\"]";
    dbg(T...);
}
#define debug(...) cerr<<"["<<#__VA_ARGS__<<"]:[\"",dbg(__VA_ARGS__)

const int mxn=1003;
vector<vector<int>> adj,p;
vector<int> group[mxn];
int n;

vector<int> par;
int findp(int x) {
    while(par[x]!=x) par[x]=par[par[x]],x=par[x]; return x;
}
void unionset(int u,int v) {
    int U=findp(u),V=findp(v);
    par[U]=V;
}
bool solve(int root) {
    int sz=group[root].size();
    if(sz==1) return true;
    if(sz==2) {
        int u=group[root][0];
        int v=group[root][1];
        adj[u][v]=adj[v][u]=1;
        return p[u][v]!=2;
    }
    vector<bool> flag(sz,false);
    vector<int> head;
    for(int i=0;i<sz;i++) {
        if(flag[i]) continue;
        flag[i]=true;
        bool have=false;
        int u=group[root][i];
        for(int j=0;j<sz;j++) {
            if(flag[j]) continue;
            int v=group[root][j];
            if(p[u][v]==1) {
                have=true;
                adj[u][v]=adj[v][u]=1;
                flag[j]=true;
            }
        }
        if(have) head.push_back(i);
    }
    if(head.empty()) return false;
    int len=head.size();
    if(len==1) return true;
    if(len==2) return false;
    for(int i=0;i<len;i++) {
        for(int j=0;j<len;j++) {
            int u=group[root][head[i]];
            int v=group[root][head[j]];
            if(p[u][v]!=2) return false;
        }
    }
    for(int i=0;i<len;i++) {
        int u=group[root][head[i]];
        int v=group[root][head[(i+1)%len]];
        adj[u][v]=adj[v][u]=1;
    }
    return true;
}

int construct(std::vector<std::vector<int>> P) {
    p=P;
	n=p.size(); par.resize(n);
	iota(all(par),0);
//	debug(par);
	adj.resize(n,vector<int>(n,0));
	for(int i=0;i<n;i++) {
        for(int j=i+1;j<n;j++) {
            if(p[i][j]!=0) {
                unionset(i,j);
            }
        }
	}
	for(int i=0;i<n;i++) {
        par[i]=findp(par[i]);
	}
	for(int i=0;i<n;i++) {
        for(int j=i+1;j<n;j++) {
            if(p[i][j] and findp(i)!=findp(j)) return 0;
            else if(!p[i][j] and findp(i)==findp(j)) return 0;
            else if(p[i][j]>2) return 0;
        }
	}
    for(int i=0;i<n;i++) {
        par[i]=findp(i);
        group[par[i]].push_back(i);
    }
    vector<bool> flag(n+1,false);
    for(int i=0;i<n;i++) {
        if(flag[par[i]]) continue;
        flag[par[i]]=true;
        bool ok=solve(par[i]);
        if(!ok) return 0;
    }
    for(int i=0;i<n;i++) adj[i][i]=0;
    build(adj);
    return 1;
}

Compilation message (stderr)

supertrees.cpp: In function 'int findp(int)':
supertrees.cpp:38:5: warning: this 'while' clause does not guard... [-Wmisleading-indentation]
   38 |     while(par[x]!=x) par[x]=par[par[x]],x=par[x]; return x;
      |     ^~~~~
supertrees.cpp:38:51: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'while'
   38 |     while(par[x]!=x) par[x]=par[par[x]],x=par[x]; return x;
      |                                                   ^~~~~~

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