Submission #884637

#	Time	Username	Problem	Language	Result	Execution time	Memory
884637		tsumondai	Hard route (IZhO17_road)	C++14	100 / 100	586 ms	155988 KiB

road

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

#define int long long
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define foru(i, l, r) for(int i = l; i <= r; i++)
#define ford(i, r, l) for(int i = r; i >= l; i--)
#define __TIME  (1.0 * clock() / CLOCKS_PER_SEC)

typedef pair<int, int> ii;
typedef pair<ii, int> iii;
typedef pair<ii, ii> iiii;

const int N = 1e6 + 5;

const int oo = 1e9, mod = 1e9 + 7;

int par[N], in[N], cnt[N], n, ans, res;
vector<int> adj[N];

bool maximize(int &a, const int b) {
    if (a < b) {
        a = b;
        return true;
    } return false;
}

void dfs(int u) {
    cnt[u] = 1;
    in[u] = 1;
    for (auto v : adj[u]) {
        if (v == par[u]) continue;
        par[v] = u;
        dfs(v);
        if (maximize(in[u], in[v] + 1)) cnt[u] = 0;
        if (in[u] == in[v] + 1) {
            cnt[u] += cnt[v];
        }
    }
}


void dp(int u, int out, int outc) {
    vector<ii> vt;
    if (u != 1)
        vt.emplace_back(out, outc);
    for (auto v : adj[u]) {
        if (v == par[u]) continue;
        vt.emplace_back(in[v], cnt[v]);
    }
    sort(vt.begin(), vt.end(), greater<ii>());
    if (vt.size() >= 3 && (vt[0].fi * (vt[1].fi + vt[2].fi)) >= res) {
        int curres = (vt[0].fi * (vt[1].fi + vt[2].fi)), curcnt = 0;
        int ba = 0;
        for (auto v : vt) {
            if (v.fi == vt[2].fi) ba += v.se;
        }
        if (vt[1].fi == vt[2].fi) {
            int cnt = 0;
            for (auto tmp : vt) {
                int x = tmp.fi, num = tmp.se;
                if (x == vt[1].fi) {
                    curcnt += cnt * num;
                    cnt += num;
                }
            }
        }
        else if (vt[0].fi == vt[1].fi) {
            curcnt = (vt[0].se + vt[1].se) * ba;
        }
        else  {
            curcnt = vt[1].se * ba;
        }
        if (maximize(res, curres)) ans = 0;
        ans += curcnt;
    }
    int mx1 = vt[0].fi, mx1c = 0, mx2 = 0, mx2c = 1;
    if (vt.size() >= 2) mx2 = vt[1].fi, mx2c = 0;
    for (auto tmp : vt) {
        int v = tmp.fi, num = tmp.se;
        if (v == mx1) mx1c += num;
        if (v == mx2) mx2c += num;
    }
    for (auto v : adj[u]) {
        if (v == par[u]) continue;
        if (in[v] == mx1) {
            if (cnt[v] == mx1c) dp(v, mx2 + 1, mx2c);
            else dp(v, mx1 + 1, mx1c - cnt[v]);
        }
        else dp(v, mx1 + 1, mx1c);
    }
}

void process() {
    cin >> n;
    ans = 1;
    foru(i,1,n-1) {
        int u, v;
        cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    int flag = 1, cnt = 0;
    foru(i,1,n) {
        if (adj[i].size() > 2) flag = 0;
        if (adj[i].size() == 1) cnt++;
    }
    dfs(1);
    dp(1, 0, 1);
    cout << res << ' ' << ans << '\n';
    return;
}

signed main() {
    cin.tie(0)->sync_with_stdio(false);
    //freopen(".inp", "r", stdin);
    //freopen(".out", "w", stdout);
    process();
    cerr << "Time elapsed: " << __TIME << " s.\n";
    return 0;
}

// dont stop

Compilation message (stderr)

road.cpp: In function 'void process()':
road.cpp:106:9: warning: variable 'flag' set but not used [-Wunused-but-set-variable]
  106 |     int flag = 1, cnt = 0;
      |         ^~~~

• Subtask 1: 19 / 19
• Subtask 2: 33 / 33
• Subtask 3: 48 / 48