Submission #927183

#TimeUsernameProblemLanguageResultExecution timeMemory
927183VMaksimoski008Connecting Supertrees (IOI20_supertrees)C++14
21 / 100
167 ms22304 KiB
#include <bits/stdc++.h>
#include "supertrees.h"

#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
//#define int long long

using namespace std;

using ll = long long;
using ull = unsigned long long;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;

const int mod = 1e9 + 7;
const int LOG = 20;
const int maxn = 1e5 + 5;
const double eps = 1e-9;

struct DSU {
    int n, comp;
    vector<int> par, size;

    void config(int _n) {
        n = _n + 1;
        comp = _n;
        par.resize(n+1);
        size.resize(n+1, 1);
        for(int i=1; i<=n; i++) par[i] = i;
    }

    int get(int u) {
        if(u == par[u]) return u;
        return par[u] = get(par[u]);
    }

    bool uni(int u, int v) {
        u = get(u), v = get(v);

        if(u == v) return false;
        if(size[u] < size[v]) swap(u, v);

        size[u] += size[v];
        par[v] = u;
        comp--;

        return true;
    }

    int getComp() { return comp; }
    int getSize(int u) { return size[get(u)]; }
    bool sameSet(int u, int v) { return get(u) == get(v); }
};

int construct(vector<vector<int> > p) {
    int n = p.size();
    vector<int> cnt(3);

    for(int i=0; i<n; i++)
        for(int j=0; j<n; j++) cnt[p[i][j]]++;

    if(cnt[0] + cnt[1] == n*n) {
        DSU dsu; dsu.config(n);
        vector<vector<int> > B(n, vector<int>(n, 0));

        for(int i=0; i<n; i++) {
            for(int j=0; j<n; j++) {
                if(p[i][j] == 1)
                    if(dsu.uni(i, j)) B[i][j] = B[j][i] = 1;
            }
        }

        for(int i=0; i<n; i++) {
            for(int j=0; j<n; j++) {
                if(p[i][j] == 1 && !dsu.sameSet(i, j)) return 0;
                if(p[i][j] == 0 && dsu.sameSet(i, j)) return 0;
            }
        }

        build(B);
        return 1;
    } else if(cnt[0] + cnt[2] == n*n) {
        DSU dsu, dsu2;
        dsu.config(n), dsu2.config(n);
        vector<vector<int> > B(n, vector<int>(n, 0));

        for(int i=0; i<n; i++) {
            for(int j=0; j<n; j++) {
                if(p[i][j] == 2) {
                    if(!dsu.sameSet(i, j) && !dsu2.sameSet(i, j)) {
                        dsu.uni(i, j);
                        p[i][j] = 1;
                    }  else if(dsu.sameSet(i, j) && !dsu2.sameSet(i, j)) {
                        dsu2.uni(i, j);
                        p[i][j] = 1;
                    }
                }
            }
        }

        for(int i=0; i<n; i++) {
            for(int j=0; j<n; j++) {
                if(p[i][j] == 0) {
                    if(dsu.sameSet(i, j) || dsu2.sameSet(i, j)) return 0;
                } else {
                    if(!dsu.sameSet(i, j) || !dsu2.sameSet(i, j)) return 0;
                }
            }
        }

        build(B);
        return 1;
    }
}

Compilation message (stderr)

supertrees.cpp: In function 'int construct(std::vector<std::vector<int> >)':
supertrees.cpp:59:22: warning: control reaches end of non-void function [-Wreturn-type]
   59 |     vector<int> cnt(3);
      |                      ^
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