Submission #441808

#	Time	Username	Problem	Language	Result	Execution time	Memory
441808		alan8585	Keys (IOI21_keys)	C++17	9 / 100	96 ms	17220 KiB

keys

#include <vector>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <queue>
using namespace std;

const int MAXN = 3000;
int T, in[MAXN], low[MAXN], instack[MAXN], bs[MAXN];
vector<pair<int, int>> e[MAXN];
vector<pair<int, int>> re[MAXN];
stack<int> st;
vector<vector<int>> SCC;
vector<int> flags;

void dfs(int a) {
    instack[a] = 1;
    st.push(a);
    in[a] = low[a] = ++T;
    for(pair<int, int> i : e[a]) {
        if(!in[i.first]) {
            dfs(i.first);
            low[a] = min(low[a], low[i.first]);
        } else if(instack[i.first]) {
            low[a] = min(low[a], in[i.first]);
        }
    }
    if(in[a] == low[a]) {
        int now = -1;
        SCC.push_back(vector<int>(0));
        do {
            now = st.top();
            bs[now] = (int)SCC.size() - 1;
            st.pop();
            instack[now] = 0;
            SCC.back().push_back(now);
        } while(now != a);
    }
}

set<int> has_key;
map<int, set<int>> key_can_open;
bitset<MAXN> vis;
queue<int> q;
int solve(int a, vector<int> &r) {
    int ans = 0;
    q.push(a);
    vis.reset();
    vis[a] = 1;
    key_can_open.clear();
    has_key.clear();
    for(pair<int, int> i : re[a]) {
        key_can_open[i.second].insert(i.first);
    }
    while(!q.empty()) {
        int now = q.front(); q.pop();
        ans += (int)SCC[now].size();
        for(int i : SCC[now]) {
            if(now != a)
                SCC[a].push_back(i);
            if(has_key.find(r[i]) == has_key.end()) {
                has_key.insert(r[i]);
                for(int j : key_can_open[r[i]]) {
                    if(!vis[j]) {
                        vis[j] = 1;
                        q.push(j);
                        for(pair<int, int> i : re[j]) {
                            key_can_open[i.second].insert(i.first);
                        }
                    }
                }
            }
        }
    }
    return ans;
}

std::vector<int> find_reachable(std::vector<int> r, std::vector<int> u, std::vector<int> v, std::vector<int> c) {
    std::vector<int> ans(r.size(), 0);
    int n = r.size(), m = u.size();
    for(int i = 0; i < m; i++) {
        if(r[u[i]] == c[i])
            e[u[i]].push_back(make_pair(v[i], c[i]));
        if(r[v[i]] == c[i])
            e[v[i]].push_back(make_pair(u[i], c[i]));
    }
    for(int i = 0; i < n; i++) {
        if(!in[i]) {
            dfs(i);
        }
    }
    int nmin = MAXN;
    vector<int> ansv;
    for(int i = 0; i < (int)SCC.size(); i++)
        for(int j : SCC[i])
            for(pair<int, int> k : e[j])
                if(bs[k.first] != i)
                    re[bs[k.first]].push_back(make_pair(i, k.second));
    for(int i = 0; i < (int)SCC.size(); i++) {
        int flag = 1;
        for(int j : SCC[i]) {
            for(pair<int, int> k : e[j]) {
                if(bs[k.first] != i) {
                    flag = 0;
                }
            }
        }
        flags.push_back(flag);
        if(flag) {
            int now = solve(i, r);
            if(nmin > now) {
                nmin = now;
            }
        }
    }
    for(int i = 0; i < (int)SCC.size(); i++) {
        if(flags[i] && (int)SCC[i].size() == nmin) {
            for(int j : SCC[i])
                ans[j] = 1;
        }
    }
    return ans;
}

• Subtask 1: 9 / 9
• Subtask 2: 0 / 11
• Subtask 3: 0 / 17
• Subtask 4: 0 / 30
• Subtask 5: 0 / 33