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Submission #171473

# Submission time Handle Problem Language Result Execution time Memory
171473 2019-12-28T17:49:18 Z VEGAnn Shymbulak (IZhO14_shymbulak) C++14
0 / 100
 1500 ms 14324 KB 
#include <bits/stdc++.h>
#define all(x) x.begin(),x.end()
#define sz(x) ((int)x.size())
#define PB push_back
#define MP make_pair
#define ft first
#define sd second
#define pll pair<ll, ll>
using namespace std;
typedef long long ll;
const ll OO = 1e18;
const int N = 200100;
const int M = 1010;
//const int PW = (1 << N);
vector<int> vc, g[N], cyc;
int mrk[N], n, mx1[N], mx2[N], kl1[N], kl2[N], ans = -1;
ll kans = 0;
bool in_cyc[N];

void CYCLE(int lst){
    cyc.clear();
    int it = sz(vc) - 1;
    while (1){
        cyc.PB(vc[it]);
        in_cyc[vc[it]] = 1;
        if (vc[it] == lst)
            break;
        it--;
    }
}

void dfs(int v, int p){
    if (sz(cyc) > 0) return;
    vc.PB(v);
    mrk[v] = 1;
    for (int u : g[v]){
        if (u == p) continue;
        if (mrk[u] == 0)
            dfs(u, v); else
        if (mrk[u] == 1)
            CYCLE(u);
    }
    mrk[v] = 2;
    vc.pop_back();
}

void calc_max(int v, int p){
    mx1[v] = 0; mx2[v] = -1;
    kl1[v] = 1; kl2[v] = 0;
    int ko = 1;
    for (int u : g[v]){
        if (u == p || in_cyc[u]) continue;
        calc_max(u, v);
        if (mx1[v] == mx1[u] + 1){
            kl1[v] += kl1[u];
            ko++;
        } else if (mx1[v] < mx1[u] + 1){
            swap(kl1[v], kl2[v]);
            swap(mx1[v], mx2[v]);
            kl1[v] = kl1[u];
            ko = 1;
            mx1[v] = mx1[u] + 1;
        } else if (mx2[v] == mx1[u] + 1){
            kl2[v] += kl1[u];
        } else if (mx2[v] < mx1[u] + 1) {
            kl2[v] = kl1[u];
            mx2[v] = mx1[u] + 1;
        }
    }

    if (mx1[v] < 1) return;

    if (ko > 1){
        if (mx1[v] + mx1[v] > ans){
            ans = mx1[v] + mx1[v];
            kans = 0;
        }
        if (mx1[v] + mx1[v] == ans)
            kans += ll(ko) * (ll(ko) - 1ll);
    } else {
        if (mx1[v] + mx2[v] > ans){
            ans = mx1[v] + mx2[v];
            kans = 0;
        }
        if (mx1[v] + mx2[v] == ans)
            kans += ll(kl1[v]) * ll(kl2[v]);
    }
}

int main(){
    ios_base::sync_with_stdio(0); cin.tie(0);
//    freopen("penguins.in","r",stdin); freopen("penguins.out","w",stdout);
//    freopen("in.txt","r",stdin);
    cin >> n;
    for (int i = 0; i < n; i++){
        int x, y;
        cin >> x >> y;
        x--; y--;
        g[x].PB(y);
        g[y].PB(x);
    }
    dfs(0, -1);
    for (int cr : cyc)
        calc_max(cr, -1);

    bool good = (sz(cyc) % 2 == 0);

    for (int i1 = 0; i1 < sz(cyc); i1++)
    for (int i2 = i1 + 1; i2 < sz(cyc); i2++){
        int dst = i2 - i1, n1 = cyc[i1], n2 = cyc[i2];
        dst = min(dst, sz(cyc) - dst);
        dst += mx1[n1] + mx1[n2];

        if (dst > ans){
            ans = dst;
            kans = 0;
        }

        if (dst == ans)
            kans += ll(kl1[n1]) * ll(kl1[n2]);

        if (good && (i2 - i1) == (sz(cyc) >> 1) && dst == ans)
            kans += ll(kl1[n1]) * ll(kl1[n2]);
    }
    cout << kans << '\n';
    return 0;
}

Subtask #1
0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 5112 KB Output is correct
2 Incorrect 6 ms 5112 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #2
0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 7 ms 5240 KB Output is correct
2 Incorrect 6 ms 5112 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #3
0 / 50.0

# Verdict Execution time Memory Grader output
1 Correct 88 ms 10956 KB Output is correct
2 Correct 85 ms 11512 KB Output is correct
3 Execution timed out 1550 ms 14324 KB Time limit exceeded
4 Halted 0 ms 0 KB -