Submission #1195701

#	Time	Username	Problem	Language	Result	Execution time	Memory
1195701		steveonalex	Simurgh (IOI17_simurgh)	C++20	0 / 100	0 ms	328 KiB

simurgh

#include "simurgh.h"
#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
typedef unsigned long long ull;
 
#define MASK(i) (1ULL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()
 
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
ll gcd(ll a, ll b){return __gcd(abs(a), abs(b));}
ll lcm(ll a, ll b){return abs(a) / gcd(a, b) * abs(b);}
 
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ull mask){return __builtin_popcountll(mask);}
int ctz(ull mask){return __builtin_ctzll(mask);}
int logOf(ull mask){return 63 - __builtin_clzll(mask);}
 
// mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
 
template <class T1, class T2>
    bool maximize(T1 &a, T2 b){
        if (a < b) {a = b; return true;}
        return false;
    }
 
template <class T1, class T2>
    bool minimize(T1 &a, T2 b){
        if (a > b) {a = b; return true;}
        return false;
    }
 
template <class T>
    void printArr(T container, string separator = " ", string finish = "\n", ostream &out = cout){
        for(auto item: container) out << item << separator;
        out << finish;
    }
 
template <class T>
    void remove_dup(vector<T> &a){
        sort(ALL(a));
        a.resize(unique(ALL(a)) - a.begin());
    }

namespace Sub{
    struct DSU{
        int n;
        vector<int> parent, sz;

        DSU(int _n){
            n = _n;
            parent.resize(n); sz.resize(n, 1);
            for(int i = 0; i<n; ++i) parent[i] = i;
        }

        int find_set(int u){return (u == parent[u]) ? u : (parent[u] = find_set(parent[u]));}
        bool same_set(int u, int v){return find_set(u) == find_set(v);}

        bool join_set(int u, int v){
            u = find_set(u), v = find_set(v);
            if (u != v){
                if (sz[u] < sz[v]) swap(u, v);
                parent[v] = u;
                sz[u] += sz[v];
                return true;
            }
            return false;
        }

        int get_size(int u){return sz[find_set(u)];}
    };

    const int N = 505;
    vector<pair<int, int>> graph[N];
    pair<int, int> parent[N];
    int h[N];

    void reset(int n){
        for(int i = 0; i < n; ++i) {
            graph[i].clear();
            h[i] = 0;
            parent[i] = make_pair(0, 0);
        }
    }

    void dfs(int u, int p){
        if (u == p) h[u] = 1;
        else h[u] = h[p] + 1;

        for(pair<int, int> v: graph[u]) if (v.first != p){
            parent[v.first] = make_pair(u, v.second);
            dfs(v.first, u);
        }
    }

    vector<int> solve(int n, vector<int> U, vector<int> V){
        int m = U.size();
        reset(n);
        vector<int> spanning_tree;
        DSU mst(n);
        for(int i = 0; i < m; ++i){
            if (mst.join_set(U[i], V[i])){
                graph[U[i]].push_back(make_pair(V[i], i));
                graph[V[i]].push_back(make_pair(U[i], i));
                spanning_tree.push_back(i);
            }
        }

        int og_cnt = count_common_roads(spanning_tree);
        dfs(0, 0);

        vector<int> cost(m, -1);
        vector<int> of_spanning_tree(m);
        for(int i: spanning_tree){
            of_spanning_tree[i] = true;
        }
        for(int i = 0; i < m; ++i) if (!of_spanning_tree[i]){
            vector<int> known_edges, unknown_edges;
            int u = U[i], v = V[i];
            while(u != v){
                if (h[u] < h[v]) swap(u, v);
                int e = parent[u].second;
                if (cost[e] == -1) unknown_edges.push_back(e);
                else known_edges.push_back(e);
                u = parent[u].first;
            }

            if (unknown_edges.empty()) continue;

            if (known_edges.size()){
                int j = known_edges.back();

                DSU mst(n);
                vector<int> cur_spanning_tree;
                cur_spanning_tree.push_back(i);
                mst.join_set(U[j], V[j]);
                for(int k: spanning_tree) if (k != j){
                    if (mst.join_set(U[k], V[k]))
                        cur_spanning_tree.push_back(k);
                }
                int cur_cnt = count_common_roads(cur_spanning_tree);
                cost[i] = cost[j] + cur_cnt - og_cnt;

                for(int j: unknown_edges){
                    DSU mst(n);
                    vector<int> cur_spanning_tree;
                    cur_spanning_tree.push_back(i);
                    mst.join_set(U[j], V[j]);
                    for(int k: spanning_tree) if (k != j){
                        if (mst.join_set(U[k], V[k]))
                            cur_spanning_tree.push_back(k);
                    }
                    int cur_cnt = count_common_roads(cur_spanning_tree);
                    cost[j] = cost[i] - cur_cnt + og_cnt;
                }
            }
            else{ // covering no edge wtf
                vector<int> diff;
                for(int j: unknown_edges){
                    DSU mst(n);
                    vector<int> cur_spanning_tree;
                    cur_spanning_tree.push_back(i);
                    mst.join_set(U[j], V[j]);
                    for(int k: spanning_tree) if (k != j){
                        if (mst.join_set(U[k], V[k]))
                            cur_spanning_tree.push_back(k);
                    }
                    int cur_cnt = count_common_roads(cur_spanning_tree);
                    diff.push_back(cur_cnt - og_cnt);
                }
                pair<int,int> range = make_pair(1, -1);
                for(int i: diff){
                    minimize(range.first, i);
                    maximize(range.second, i);
                }

                if (range == make_pair(0, 0)){
                    cost[i] = 0;
                    for(int j: unknown_edges) cost[j] = 0;
                }
                else if (range.second == 1){
                    cost[i] = 1;
                    for(int j = 0; j < (int) unknown_edges.size(); ++j)
                        cost[unknown_edges[j]] = 1 - diff[j];
                }
                else{
                    cost[i] = 0;
                    for(int j = 0; j < (int) unknown_edges.size(); ++j)
                        cost[unknown_edges[j]] = -diff[j];
                }
            }
        }

        for(int i = 0; i < m; ++i) if (cost[i] == -1 && of_spanning_tree[i]) // bridge
            cost[i] = 1; 
        while(true){
            DSU mst(n);
            vector<int> pending;
            for(int i = 0; i < m; ++i) if (cost[i] == -1){
                if (mst.join_set(U[i], V[i])){
                    pending.push_back(i);
                }
            }

            if (pending.empty()) break;

            vector<int> cur_spanning_tree = pending;
            int cur_cost = 0;
            for(int i: spanning_tree) {
                if (mst.join_set(U[i], V[i])){
                    cur_spanning_tree.push_back(i);
                    cur_cost -= cost[i];
                }
            }
            cur_cost += count_common_roads(cur_spanning_tree);
            int last = -1;
            for(int i: pending) cost[i] = 0;
            for(int it = 1; it <= cur_cost; ++it){
                int l = last + 1, r = pending.size() - (cur_cost - it) - 1;
                while(l < r){
                    int mid = (l + r) >> 1;
                    vector<int> cur_spanning_tree;
                    for(int i = 0; i <= mid; ++i) {
                        cur_spanning_tree.push_back(pending[i]);
                    }
                    int cur_cost = 0;
                    for(int i: spanning_tree) {
                        if (mst.join_set(U[i], V[i])){
                            cur_spanning_tree.push_back(i);
                            cur_cost -= cost[i];
                        }
                    }
                    cur_cost += count_common_roads(cur_spanning_tree);
                    if (cur_cost >= it) r = mid;
                    else l = mid + 1;
                }
                cost[pending[l]] = 1;
                last = l;
            }
        }

        vector<int> ans;
        for(int i = 0; i < m; ++i) if (cost[i]) ans.push_back(i);

        if (ans.size() != n-1) assert(false);
        if (count_common_roads(ans) != n-1) assert(false);
        return ans;
    }
}

vector<int> find_roads(int n, vector<int> u, vector<int> v){
    return Sub::solve(n, u, v);
}

// int main(void){
//     ios::sync_with_stdio(0);cin.tie(0); cout.tie(0);

//     clock_t start = clock();

//     cerr << "Time elapsed: " << clock() - start << " ms!\n";

//     return 0;
// }

• Subtask 1: 0 / 13
• Subtask 2: 0 / 17
• Subtask 3: 0 / 21
• Subtask 4: 0 / 19
• Subtask 5: 0 / 30