Submission #441788

#	Time	Username	Problem	Language	Result	Execution time	Memory
441788		alan8585	Keys (IOI21_keys)	C++17	9 / 100	268 ms	51868 KiB

keys

#include <vector>
#include <stack>
using namespace std;

const int MAXN = 300100;
int T, in[MAXN], low[MAXN], instack[MAXN], bs[MAXN];
vector<int> e[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(int i : e[a]) {
        if(!in[i]) {
            dfs(i);
            low[a] = min(low[a], low[i]);
        } else if(instack[i]) {
            low[a] = min(low[a], in[i]);
        }
    }
    if(in[a] == low[a]) {
        int now = -1;
        SCC.push_back(vector<int>(0));
        do {
            now = st.top();
            st.pop();
            SCC.back().push_back(now);
            bs[now] = SCC.size();
            instack[now] = 0;
        } while(now != a);
    }
}

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(v[i]);
        if(r[v[i]] == c[i])
            e[v[i]].push_back(u[i]);
    }
    for(int i = 0; i < n; i++) {
        if(!in[i]) {
            dfs(i);
        }
    }
    int nmin = MAXN;
    for(int i = 0; i < (int)SCC.size(); i++) {
        int flag = 1;
        for(int j : SCC[i]) {
            for(int k : e[j]) {
                if(bs[k] != i + 1)
                    flag = 0;
            }
        }
        flags.push_back(flag);
        if(flag) {
            nmin = min(nmin, (int)SCC[i].size());
        }
    }
    for(int i = 0; i < (int)SCC.size(); i++) {
        if(flags[i] && SCC[i].size() == nmin) {
            for(int j : SCC[i])
                ans[j] = 1;
        }
    }
    return ans;
}

Compilation message (stderr)

keys.cpp: In function 'std::vector<int> find_reachable(std::vector<int>, std::vector<int>, std::vector<int>, std::vector<int>)':
keys.cpp:66:38: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   66 |         if(flags[i] && SCC[i].size() == nmin) {
      |                        ~~~~~~~~~~~~~~^~~~~~~

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