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ID	Problem	Submitter	Result	Time	Memory	Language	File size	Submit time	Judge time
#75445	#5307. Subgraph Isomorphism	team1377^#	WA	49ms	6600kb	C++14	2.5kb	2023-02-05 10:43:38	2023-10-15 17:24:16

Judging History

This is the latest submission verdict.

[2023-10-15 17:24:16]
管理员手动重测本题所有提交记录

Verdict: WA
Time: 49ms
Memory: 6600kb

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[2023-08-10 23:21:45]
System Update: QOJ starts to keep a history of the judgings of all the submissions.

[2023-02-05 10:43:38]
Judged

Verdict: 0
Time: 73ms
Memory: 6608kb

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[2023-02-05 10:43:38]
Submitted

answer

#include <bits/stdc++.h>

using namespace std;

const int N = 1e5 + 5;

vector<int> G[N];
vector<int> S, cyc;
int inS[N];

void dfs(int x, int fa = -1)
{
    S.push_back(x);
    inS[x] = 1;
    for (int i = 0; i < G[x].size(); ++i) {
        int v = G[x][i];
        if (v == fa) {
            continue;
        }
        if (inS[v]) {
            int p;
            do {
                p = S.back();
                S.pop_back();
                cyc.push_back(p);
            } while (p != v);
            return;
        }
        dfs(v, x);
        if (cyc.size()) {
            return;
        }
    }
    S.pop_back();
    inS[x] = 0;
    return;
}

int base[N], siz[N];

int hhash(int x, int fa = -1, int fa2 = -1)
{
    siz[x] = 1;
    vector<int> tmp;
    for (int i = 0; i < G[x].size(); ++i) {
        int v = G[x][i];
        if (v == fa || v == fa2) {
            continue;
        }
        tmp.push_back(hhash(v, x));
        siz[x] += siz[v];
    }
    sort(tmp.begin(), tmp.end());
    int val = siz[x];
    for (int i = 0; i < tmp.size(); ++i) {
        val = (1ll * val * base[i] + tmp[i]) % 998244353;
    }
    return val;
}

signed main()
{
    mt19937 rnd;
    for (int i = 0; i < N; ++i) {
        base[i] = rnd() % 998244353;
    }
    int T;
    scanf("%d", &T);
    while (T--) {
        int n, m;
        scanf("%d%d", &n, &m);
        for (int i = 1; i <= n; ++i) {
            G[i].clear();
            inS[i] = 0;
        }
        for (int i = 1; i <= m; ++i) {
            int x, y;
            scanf("%d%d", &x, &y);
            G[x].push_back(y);
            G[y].push_back(x);
        }
        if (m == n - 1) {
            puts("YES");
        } else if (m != n) {
            puts("NO");
        } else {
            S.clear();
            cyc.clear();
            dfs(1);
            if (!cyc.size()) {
                puts("NO");
            } else {
                vector<int> hs;
                for (int i = 0; i < cyc.size(); ++i) {
                    hs.push_back(hhash(cyc[i], cyc[(i - 1 + cyc.size()) % cyc.size()], cyc[(i + 1) % cyc.size()]));
                }
                int flag = 1;
                for (int i = 2; i < cyc.size(); ++i) {
                    flag &= hs[i] == hs[i - 2];
                }
                if (flag) {
                    puts("YES");
                } else {
                    puts("NO");
                }
            }
        }
    }
    return 0;
}

Source code, Language: C++14

Details

Tip: Click on the bar to expand more detailed information

Test #1:

score: 100

Accepted

time: 2ms

memory: 6600kb

input:

output:

YES
YES
NO
YES

result:

ok 4 token(s): yes count is 3, no count is 1

Test #2:

score: -100

Wrong Answer

time: 49ms

memory: 6372kb

input:

output:

YES
YES
YES
YES
YES
NO
YES
NO
NO
YES
YES
NO
NO
NO
NO
NO
NO
YES
NO
NO
NO
NO
YES
NO
NO
NO
NO
NO
NO
NO
YES
YES
NO
YES
YES
NO
NO
NO
YES
NO
NO
NO
NO
NO
YES
NO
NO
NO
YES
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
YES
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
YES
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO...

result:

wrong answer expected NO, found YES [374th token]