Submission #488904

#	Time	Username	Problem	Language	Result	Execution time	Memory
488904		Victor	Logičari (COCI21_logicari)	C++17	110 / 110	211 ms	27312 KiB

Main

#include <bits/stdc++.h>

using namespace std;

#define rep(i, a, b) for (int i = (a); i < (b); ++i)
#define per(i, a, b) for (int i = (b - 1); i >= (a); --i)
#define trav(a, x) for (auto &a : x)

#define all(x) x.begin(), x.end()
#define sz(x) x.size()
#define pb push_back
#define debug(x) cout << #x << " = " << x << endl

#define umap unordered_map
#define uset unordered_set

typedef pair<int, int> ii;
typedef pair<int, ii> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<vi> vvi;

typedef long long ll;
typedef pair<ll, ll> pll;
typedef vector<ll> vll;
typedef vector<pll> vpll;

const int INF = 1'000'000'007;

struct union_find {
    vi p, rank;
    union_find(int n) {
        p.resize(n);
        rep(i, 0, n) p[i] = i;
        rank.assign(n, 0);
    }

    int find(int i) { return p[i] == i ? i : p[i] = find(p[i]); }
    bool same(int i, int j) { return find(i) == find(j); }
    void union_set(int i, int j) {
        i = find(i);
        j = find(j);
        if (i == j) return;

        if (rank[i] < rank[j]) swap(i, j);
        p[j] = i;
        if (rank[i] == rank[j]) ++rank[i];
    }
};

vi graph[100001];
int root, rem, memo[100001][2][2][2][2], dfs_parent[100001];

int dp(int u, bool take_cur, bool parent, bool taken, bool root_taken) {
    if (u == rem) {
        if (taken != take_cur) return INF;
        if (root_taken && parent) return INF;
    }

    int &ans = memo[u][take_cur][parent][taken][root_taken];
    if (ans != -1) return ans;

    if(u==rem)parent |= root_taken;
    ans = 0;
    int cnt = 0;
    ll mn = INF,cur_ans=0;

    trav(v, graph[u]) if (v != dfs_parent[u]) {
        dfs_parent[v]=u;
        ++cnt;
        ll val = dp(v, 0, take_cur, taken, root_taken);
        cur_ans+=val;
        if (!parent) {
            ll diff = dp(v,1,take_cur,taken,root_taken)-val;
            mn=min(mn,diff);
        }
    }

    if(!parent&&!cnt)return ans= INF;

    if(!parent)ans=min((ll)INF,cur_ans+mn);
    else ans=min((ll)INF,cur_ans);

    //cout<<"u = "<<u+1<<" take_cur = "<<take_cur<<" parent = "<<parent<<" ans = "<<ans<<endl;
    return ans+take_cur;
}

int main() {
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit);

    memset(memo, -1, sizeof(memo));
    int n;

    cin >> n;
    union_find ufds(n);
    rep(i, 0, n) {
        int u, v;
        cin >> u >> v;
        if (ufds.same(--u, --v)) {
            root = u;
            rem = v;
            continue;
        }

        graph[u].pb(v);
        graph[v].pb(u);
        ufds.union_set(u, v);
    }

    dfs_parent[root] = root;
    int ans = INF;
    ans = dp(root, 1, 0, 0, 1);
    ans = min(ans, dp(root, 1, 1, 1, 1));
    ans = min(ans, dp(root, 0, 0, 0, 0));
    ans = min(ans, dp(root, 0, 1, 1, 0));

    if (ans > n) ans = -1;
    cout << ans << endl;
    return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 40 / 40
• Subtask 4: 50 / 50