제출 #1036322

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1036322		adaawf	Hard route (IZhO17_road)	C++17	0 / 100	14 ms	24532 KiB

road

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
vector<int> g[500005];
int dd[500005], da[500005], d[500005], z = 0;
long long int lazy[2000005], f[500005], t[2000005];
void push(int v) {
    t[v * 2] += lazy[v];
    t[v * 2 + 1] += lazy[v];
    lazy[v * 2] += lazy[v];
    lazy[v * 2 + 1] += lazy[v];
    lazy[v] = 0;
}
void update(int v, int tl, int tr, int l, int r, int y) {
    if (l > r) return;
    if (tl == l && tr == r) {
        t[v] += y;
        lazy[v] += y;
        return;
    }
    push(v);
    int mid = (tl + tr) / 2;
    update(v * 2, tl, mid, l, min(r, mid), y);
    update(v * 2 + 1, mid + 1, tr, max(l, mid + 1), r, y);
    t[v] = max(t[v * 2], t[v * 2 + 1]);
}
int sum(int v, int tl, int tr, int l, int r) {
    if (l > r) return 0;
    if (tl == l && tr == r) {
        return t[v];
    }
    push(v);
    int mid = (tl + tr) / 2;
    return max(sum(v * 2, tl, mid, l, min(r, mid)), sum(v * 2 + 1, mid + 1, tr, max(l, mid + 1), r));
}
long long int res = 0, h = 0;
void dfs(int x, int p) {
    dd[x] = ++z;
    for (int w : g[x]) {
        if (w == p) continue;
        d[w] = d[x] + 1;
        dfs(w, x);
    }
    da[x] = z;
}
void dfs2(int x, int p) {
    vector<long long int> v;
    vector<pair<long long int, long long int>> vv;
    for (int w : g[x]) {
        if (w == p) continue;
        update(1, 1, z, dd[w], da[w], -2);
        update(1, 1, z, 1, z, 1);
        dfs2(w, x);
        update(1, 1, z, dd[w], da[w], 2);
        update(1, 1, z, 1, z, -1);
        f[x] = max(f[x], f[w] + 1);
        v.push_back(f[w] + 1);
    }
    if (v.size() < 2) return;
    sort(v.begin(), v.end(), greater<long long int>());
    long long int c = 0, k = 0, d = max(sum(1, 1, z, 1, dd[x] - 1), sum(1, 1, z, da[x] + 1, z));
    for (long long int w : v) {
        if (w != k && k != 0) {
            vv.push_back({k, c});
            c = 0;
        }
        k = w;
        c++;
    }
    vv.push_back({k, c});
    long long int hh, kk;
    hh = d * (v[0] + v[1]);
    if (vv[0].second >= 2) {
        kk = (vv[0].second * (vv[0].second - 1) / 2);
    }
    else {
        if (vv.size() == 1) exit(0);
        kk = vv[0].second * vv[1].second;
    }
    if (res < hh) {
        res = hh;
        h = kk;
    }
    else if (res == hh) h += kk;
    if (v.size() < 3) return;
    hh = v[0] * (v[1] + v[2]);
    if (vv[0].second >= 3) {
        kk = vv[0].second * (vv[0].second - 1) / 2;
    }
    else if (vv.size() == 1) exit(0);
    else if (vv[0].second + vv[1].second >= 3) {
        if (vv[0].second == 1) {
            kk = vv[1].second * (vv[1].second - 1) / 2;
        }
        else {
            kk = vv[1].second * 2;
        }
    }
    else {
        if (vv.size() <= 2) exit(0);
        kk = vv[2].second;
    }
    if (res < hh) {
        res = hh;
        h = kk;
    }
    else if (res == hh) h += kk;
}
int main() {
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    int n, r;
    cin >> n;
    for (int i = 1; i < n; i++) {
        int u, v;
        cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    for (int i = 1; i <= n; i++) {
        if (g[i].size() > 1) {
            r = i;
            break;
        }
    }
    dfs(r, 0);
    for (int i = 1; i <= n; i++) {
        update(1, 1, n, dd[i], dd[i], d[i]);
    }
    dfs2(r, 0);
    cout << res << " " << h;
}

컴파일 시 표준 에러 (stderr) 메시지

road.cpp: In function 'int main()':
road.cpp:131:9: warning: 'r' may be used uninitialized in this function [-Wmaybe-uninitialized]
  131 |     dfs2(r, 0);
      |     ~~~~^~~~~~

• Subtask 1: 0 / 19
• Subtask 2: 0 / 33
• Subtask 3: 0 / 48