제출 #405565

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
405565		ernest0_0abreu	Inside information (BOI21_servers)	C++17	30 / 100	3569 ms	52316 KiB

servers

#include <bits/stdc++.h>
using namespace std;

const int MAXN = 2e5, INF = 2e9;
vector<pair<int,int>> g[MAXN], C;
vector<pair<int,pair<int,int>>> Q;
vector<pair<int,pair<char,int>>> ansv;

int lcaM[MAXN][20], lca[MAXN][20], lcaC[MAXN][20];
int lvl[MAXN];
int dp[MAXN], dpEdge[MAXN][2];

    void dfs(int u, int p, int lastedge){
        for(auto x : g[u]){
            int v = x.first, w = x.second;
            if(v != p){
                lca[v][0] = u;
                lcaM[v][0] = w;
                if(w > lastedge)
                    lcaC[v][0] = 1;
                lvl[v] = lvl[u] + 1;
                dfs(v , u , w);
            }
        }
    }

    pair<int,int> LCA(int a, int b){
        int _lca, _max = 0;

        if(lvl[a] > lvl[b]) swap(a,b);
        for(int i = 19; i >= 0; --i){
            if(lvl[lca[b][i]] >= lvl[a]){
                _max = max(_max , lcaM[b][i]);
                b = lca[b][i];
            }
        }
        for(int i = 19; i >= 0; --i){
            if(lca[a][i] != lca[b][i]){
                _max = max(_max , lcaM[a][i]);
                _max = max(_max , lcaM[b][i]);
                a = lca[a][i];
                b = lca[b][i];
            }
        }
        // cerr << a << ' ' << b << '\n';

        if(a != b){
            _max = max(_max , lcaM[a][0]);
            _max = max(_max , lcaM[b][0]);
            _lca = lca[a][0];
        }
        else _lca = a;

        return {_lca , _max};
    }

    bool Check(int a, int b, int _lca){

        if(a == b) return true;


        int cost = 0;
        for(int i = 19; i >= 0; --i){
            if(lvl[lca[a][i]] > lvl[_lca]){
                cost += lcaC[a][i];
                a = lca[a][i];
            }
        }
        if(cost) 
            return false;

        cost = 0; int original_b = b;
        for(int i = 19; i >= 0; --i){
            if(lvl[lca[b][i]] > lvl[_lca]){
                cost += lcaC[b][i];
                b = lca[b][i];
            }
        }

        if(cost != lvl[original_b] - lvl[b]) 
            return false;

        if(a == _lca || b == _lca)
            return true;
        
        if(lcaM[a][0] < lcaM[b][0])
            return true;

        return false;
    }

    int DPEdge(int u, int id, int dir){
        if(dpEdge[id][dir] != -1)  return dpEdge[id][dir];
        dpEdge[id][dir] = 1;
        for(auto x : g[u]){
            int v = x.first, w = x.second;
            if(id == w) continue;
            if(w > id)
                dpEdge[id][dir] += DPEdge(v , w , (u < v));
        }
        return dpEdge[id][dir];
    }

int main(){
    ios_base::sync_with_stdio(false); cin.tie(nullptr);

    int n, q;
    cin >> n >> q;
    for(int i = 1; i < n+q; ++i){
        char c;
        cin >> c;
        if(c == 'S'){
            int u, v;
            cin >> u >> v;
            g[u].push_back({v,i});
            g[v].push_back({u,i});
        }   
        if(c == 'Q'){ 
            int a, b;
            cin >> a >> b;
            Q.push_back({i , {a,b}});
        }
        if(c == 'C'){
            int x;
            cin >> x;
            C.push_back({i,x});
        }
    }

{   //Subproblem for Query 'Q'
    lvl[1] = 1;
    dfs(1 , 0 , INF);

    for(int k = 1; k < 20; ++k)
        for(int i = 1; i <= n; ++i){
            lca[i][k] = lca[lca[i][k-1]][k-1];
            lcaM[i][k] = max(lcaM[i][k-1] , lcaM[lca[i][k-1]][k-1]);
            lcaC[i][k] = lcaC[i][k-1] + lcaC[lca[i][k-1]][k-1];
        }

    for(auto x : Q){
        int a, b, w;
        a = x.second.first, b = x.second.second;
        w = x.first;

        pair<int,int> p = LCA(a , b);
        int _lca = p.first, _max = p.second;

        // cerr << _lca << '\n';
        bool ans = Check(b , a, _lca);

        if(_max > w)
            ans = false;

        if(ans)
            ansv.push_back({w , {'Q' , 1}});
        else
            ansv.push_back({w , {'Q' , 0}});
    }
}
    
    for(int i = 1; i < n+q; ++i)
        dpEdge[i][0] = dpEdge[i][1] = -1;

    for(int i = 1; i <= n; ++i)
        for(auto x : g[i]){
            int v = x.first, w = x.second;
            dp[i] += DPEdge(v , w , (i < v));
        }

    for(auto x : C)
        ansv.push_back({x.first , {'C' , dp[x.second] + 1}});

    sort(ansv.begin() , ansv.end());

    for(auto x : ansv){
        if(x.second.first == 'Q')
            if(x.second.second)
                cout << "yes\n";
            else
                cout << "no\n";
        // else
        //     cout << x.second.second << '\n';
    }

    return 0;
}

컴파일 시 표준 에러 (stderr) 메시지

servers.cpp: In function 'int main()':
servers.cpp:177:11: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
  177 |         if(x.second.first == 'Q')
      |           ^

• Subtask 1: 2.5 / 2.5
• Subtask 2: 0 / 2.5
• Subtask 3: 0 / 2.5
• Subtask 4: 0 / 2.5
• Subtask 5: 5 / 5
• Subtask 6: 0 / 5
• Subtask 7: 10 / 10
• Subtask 8: 0 / 10
• Subtask 9: 12.5 / 12.5
• Subtask 10: 0 / 12.5
• Subtask 11: 0 / 17.5
• Subtask 12: 0 / 17.5