Submission #765280

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
765280	2023-06-24T10:15:24 Z	oyber	Joker (BOI20_joker)	C++14	25 / 100	73 ms	5580 KB

Joker

#include <cstdio>
#include <vector>
#include <algorithm>
#include <functional>
using namespace std;

vector<int> u;
vector<int> s;
vector<int> p;

int find(int n) {
    if (u[n] == n) return n;
    return find(u[n]);
}

int parity(int n) {
    if (u[n] == n) return 0;
    return parity(u[n])^p[n];
}

void unite(int a, int b) {
    int ap = find(a);
    int bp = find(b);
    if (s[bp] > s[ap]) {
        swap(a, b);
        swap(ap, bp);
    }
    u[bp] = ap;
    s[ap] += s[bp];
    if (parity(a) == parity(b)) {
        p[bp] = 1;
    }
}

int main() {
    int n, m, qn;
    scanf("%d %d %d", &n, &m, &qn);

    u.resize(n);
    s.resize(n, 1);
    p.resize(n);

    for (int i = 0; i < n; i++) {
        u[i] = i;
    }

    vector<pair<int, int>> e(m);
    for (int i = 0; i < m; i++) {
        int a, b; 
        scanf("%d %d", &a, &b);
        a--;b--;
        e[i] = make_pair(a, b);
        //printf("%d %d %d\n", a, b, i);
    }

    int cycle = -1;
    for (int j = m-1; j >= 0; j--) {
        int a = e[j].first;
        int b = e[j].second;
        //printf("%d: (%d %d) (%d %d) (%d %d)\n", j, a, b, find(a), find(b), parity(a), parity(b));
        if (find(a) == find(b)) {
            if (parity(a) == parity(b)) {
                cycle = j;
                break;
            }
        } else {
            unite(a, b);
        }
    }
    //printf("%d\n", cycle);
    for (int i = 0; i < qn; i++) {
        int l, r;
        scanf("%d %d", &l, &r);
        l--;r--;

        if (r < cycle) {
            printf("YES\n");
        } else {
            printf("NO\n");
        }
    }
}

Compilation message

Joker.cpp: In function 'int main()':
Joker.cpp:37:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   37 |     scanf("%d %d %d", &n, &m, &qn);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Joker.cpp:50:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   50 |         scanf("%d %d", &a, &b);
      |         ~~~~~^~~~~~~~~~~~~~~~~
Joker.cpp:73:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   73 |         scanf("%d %d", &l, &r);
      |         ~~~~~^~~~~~~~~~~~~~~~~

Subtask #1
0 / 6.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	1 ms	212 KB	Output is correct
2	Correct	1 ms	212 KB	Output is correct
3	Incorrect	0 ms	284 KB	Output isn't correct
4	Halted	0 ms	0 KB	-

Subtask #2
0 / 8.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	1 ms	212 KB	Output is correct
2	Correct	1 ms	212 KB	Output is correct
3	Incorrect	0 ms	284 KB	Output isn't correct
4	Halted	0 ms	0 KB	-

Subtask #3
25.0 / 25.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	1 ms	212 KB	Output is correct
2	Correct	1 ms	212 KB	Output is correct
3	Correct	73 ms	4808 KB	Output is correct
4	Correct	66 ms	5580 KB	Output is correct
5	Correct	63 ms	5500 KB	Output is correct
6	Correct	63 ms	4184 KB	Output is correct
7	Correct	62 ms	4172 KB	Output is correct
8	Correct	62 ms	4044 KB	Output is correct
9	Correct	63 ms	4416 KB	Output is correct
10	Correct	63 ms	5540 KB	Output is correct
11	Correct	65 ms	4168 KB	Output is correct
12	Correct	62 ms	5120 KB	Output is correct
13	Correct	64 ms	3228 KB	Output is correct
14	Correct	61 ms	3756 KB	Output is correct
15	Correct	63 ms	4776 KB	Output is correct
16	Correct	62 ms	5356 KB	Output is correct