Submission #930540

#	Time	Username	Problem	Language	Result	Execution time	Memory
930540		Ghulam_Junaid	Joker (BOI20_joker)	C++17	39 / 100	2094 ms	211884 KiB

Joker

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

const int N = 2e5 + 3;
int n, m, q, vis_nq[N], par[N], col[N];
vector<pair<int, int>> g[N], atl[N];
pair<int, int> edge[N];
vector<int> S[N];
bool ans[N];

int root(int v){
    return (par[v] == -1 ? v : root(par[v]));
}

inline bool merge(int u, int v){
    int r1 = root(u);
    int r2 = root(v);

    if (r1 == r2)
        return (col[u] != col[v]);

    if (S[r2].size() > S[r1].size())
        swap(r1, r2);
    par[r2] = r1;

    int take = 0;
    if (col[u] == col[v])
        take = 3;

    for (int x : S[r2]){
        col[x] ^= take;
        S[r1].push_back(x);
    }
    S[r2].clear();
    return 1;
}

int main(){
    scanf("%d%d%d", &n, &m, &q);
    for (int i = 1; i <= m; i ++){
        int u, v;
        scanf("%d%d", &u, &v);

        g[u].push_back({i, v});
        g[v].push_back({i, u});
        edge[i] = {u, v};
    }

    int mx = 0;
    for (int i = 0; i < q; i ++){
        int l, r;
        scanf("%d%d", &l, &r);
        mx = max(mx, l);
        atl[l].push_back({r, i});
    }

    for (int i = 1; i <= m; i ++){
        sort(atl[i].begin(), atl[i].end());
        reverse(atl[i].begin(), atl[i].end());
    }

    for (int i = 1; i <= mx; i ++){
        if (atl[i].size() == 0) continue;

        for (int j = 1; j <= n; j ++){
            S[j] = {j};
            par[j] = -1;
            col[j] = 1;
        }

        bool even = 1;
        for (int j = 1; j < i; j ++)
            even &= merge(edge[j].first, edge[j].second);

        int x = m;
        for (auto [r, id] : atl[i]){
            for (int j = r + 1; j <= x; j ++)
                even &= merge(edge[j].first, edge[j].second);
            x = r;

            if (even)
                ans[id] = 0;
            else
                ans[id] = 1;
        }
    }

    for (int i = 0; i < q; i ++){
        if (ans[i])
            printf("YES\n");
        else
            printf("NO\n");
    }
}

Compilation message (stderr)

Joker.cpp: In function 'int main()':
Joker.cpp:39:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   39 |     scanf("%d%d%d", &n, &m, &q);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~
Joker.cpp:42:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   42 |         scanf("%d%d", &u, &v);
      |         ~~~~~^~~~~~~~~~~~~~~~
Joker.cpp:52:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   52 |         scanf("%d%d", &l, &r);
      |         ~~~~~^~~~~~~~~~~~~~~~

• Subtask 1: 6 / 6
• Subtask 2: 8 / 8
• Subtask 3: 25 / 25
• Subtask 4: 0 / 10
• Subtask 5: 0 / 22
• Subtask 6: 0 / 29