oj.uz

Submission #635621

# Submission time Handle Problem Language Result Execution time Memory
635621 2022-08-26T13:58:46 Z 406 Subtree (INOI20_subtree) C++17
12 / 100
 71 ms 34728 KB 
#include <bits/stdc++.h>
using ll = long long;
using namespace std;

#define forn(a, b) for (int a = 0; a < (b); a++)
#define rofn(a, b) for (int a = (b) - 1; a >= 0; a--)
#define LOG(a) (31 - __builtin_clz(a))
#define chmx(a, b) a = max(a, b)
#define chmn(a, b) a = min(a, b)
#define pb push_back
#define gc() (p1==p2&&(p2=(p1=buf)+fread(buf,1,1<<21,stdin),p1==p2)?EOF:*p1++)
char buf[1<<21],*p1,*p2;

inline int read() {
	int x = 0, f = 1; char c;
	while(!isdigit(c = gc())) if(c=='-') f=-1;
	while(isdigit(c)) x = (x<<3)+(x<<1)+(c^48), c = gc();
	return x * f;
}

const ll INFL = 1ll << 60;
const int INF = 1 << 29;
const int N = 1e5 + 50;
const int MOD = 1e9 + 7;

ll pw(ll a, ll b) {
    a %= MOD;
    b %= (MOD - 1);
    ll re = 1;
    while (b) {
        if (b & 1)
            re = (re * a) % MOD;
        a = (a * a) % MOD;
        b >>= 1;
    }
    return re;
}

ll dp[N];
int h[N], par[N], n, m;
bitset<N> mark;
vector<int> adj[N];

void dfs(int v) {
    mark[v] = true;
    dp[v] = 1;
    vector<int> unp;

    for (auto u: adj[v]) {
        if (!mark[u]) {
            par[u] = v;
            h[u] = h[v] + 1;
            dfs(u);
            dp[v] = (dp[v] * (dp[u] + 1)) % MOD;
        }
        else if (u != par[v] && h[u] > h[v]) {
            unp.pb(u);
        }
    }

    for (auto u: unp) {
        vector<ll> X;
        int last = n;
        while (u != par[v]) {
            X.pb((dp[u] * pw((dp[last] + 1), MOD - 2)) % MOD);
            if (X.back() < 0)
                X.back() += MOD;
            last = u;
            u = par[u];
        }

        dp[v] = 0;
        reverse(X.begin(), X.end());

        vector<ll> pref, P, suf;
        suf.pb(1);
        for (int i = X.size(); i >= 2; i--) {
            suf.pb((suf.back() * X[i - 1]) % MOD);
        }
        reverse(suf.begin(), suf.end());

        pref.pb(X[0]);
        for (int i = 1; i < X.size(); i++)
            pref.pb((pref.back() * X[i]) % MOD);

        P.resize(pref.size());
        partial_sum(pref.begin(), pref.end(), P.begin());

        for (int i = 2; i < X.size(); i++) {
            dp[v] += (suf[i] * P[i - 2]) % MOD;
            if (dp[v] >= MOD)
                dp[v] -= MOD;
        }

        ll kol = suf.front();
        for (int i = 1; i < X.size(); i++) {
            dp[v] += (kol * pw(X[i], MOD - 2)) % MOD;
            if (dp[v] >= MOD)
                dp[v] -= MOD;
        }
    }
}

signed main() {
    ios::sync_with_stdio(0), cin.tie(0);
    cin >> n >> m;
    for (int i = 0; i < m; i++) {
        int u, v;
        cin >> u >> v;
        u--, v--;
        adj[v].pb(u);
        adj[u].pb(v);
    }
    par[0] = -1;
    dfs(0);

    ll ans = 0;
    for (int i = 0; i < n; i++) {
        ans += dp[i];
        if (ans >= MOD)
            ans -= MOD;
    }
    cout << ans << '\n';

    return 0;
}

Compilation message

Main.cpp: In function 'void dfs(int)':
Main.cpp:83:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   83 |         for (int i = 1; i < X.size(); i++)
      |                         ~~^~~~~~~~~~
Main.cpp:89:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   89 |         for (int i = 2; i < X.size(); i++) {
      |                         ~~^~~~~~~~~~
Main.cpp:96:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   96 |         for (int i = 1; i < X.size(); i++) {
      |                         ~~^~~~~~~~~~

Subtask #1
0 / 8.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2680 KB Output is correct
2 Correct 2 ms 2644 KB Output is correct
3 Correct 2 ms 2676 KB Output is correct
4 Correct 2 ms 2680 KB Output is correct
5 Correct 1 ms 2644 KB Output is correct
6 Correct 1 ms 2644 KB Output is correct
7 Correct 2 ms 2676 KB Output is correct
8 Incorrect 2 ms 2676 KB Output isn't correct
9 Halted 0 ms 0 KB -

Subtask #2
12.0 / 12.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2644 KB Output is correct
2 Correct 5 ms 3156 KB Output is correct
3 Correct 60 ms 8560 KB Output is correct
4 Correct 55 ms 8548 KB Output is correct
5 Correct 41 ms 8516 KB Output is correct
6 Correct 38 ms 8524 KB Output is correct
7 Correct 59 ms 28796 KB Output is correct
8 Correct 67 ms 21328 KB Output is correct
9 Correct 62 ms 21344 KB Output is correct
10 Correct 46 ms 9236 KB Output is correct
11 Correct 47 ms 8720 KB Output is correct
12 Correct 59 ms 8496 KB Output is correct
13 Correct 45 ms 8524 KB Output is correct
14 Correct 54 ms 17264 KB Output is correct
15 Correct 71 ms 31956 KB Output is correct
16 Correct 71 ms 34728 KB Output is correct
17 Correct 57 ms 8592 KB Output is correct
18 Correct 61 ms 8764 KB Output is correct
19 Correct 51 ms 8832 KB Output is correct
20 Correct 35 ms 8792 KB Output is correct
21 Correct 35 ms 9032 KB Output is correct
22 Correct 34 ms 8848 KB Output is correct

Subtask #3
0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2680 KB Output is correct
2 Correct 2 ms 2644 KB Output is correct
3 Correct 2 ms 2676 KB Output is correct
4 Correct 2 ms 2680 KB Output is correct
5 Correct 1 ms 2644 KB Output is correct
6 Correct 1 ms 2644 KB Output is correct
7 Correct 2 ms 2676 KB Output is correct
8 Incorrect 2 ms 2676 KB Output isn't correct
9 Halted 0 ms 0 KB -

Subtask #4
0 / 50.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2680 KB Output is correct
2 Correct 2 ms 2644 KB Output is correct
3 Correct 2 ms 2676 KB Output is correct
4 Correct 2 ms 2680 KB Output is correct
5 Correct 1 ms 2644 KB Output is correct
6 Correct 1 ms 2644 KB Output is correct
7 Correct 2 ms 2676 KB Output is correct
8 Incorrect 2 ms 2676 KB Output isn't correct
9 Halted 0 ms 0 KB -