Submission #1086450

#	Time	Username	Problem	Language	Result	Execution time	Memory
1086450		serifefedartar	Chase (CEOI17_chase)	C++17	0 / 100	66 ms	15696 KiB

chase

#include <bits/stdc++.h>
using namespace std;
 
#define fast ios::sync_with_stdio(0);cin.tie(0)
typedef long long ll;
#define f first
#define s second
#define LOGN 21
const ll MOD = 1e9 + 7;
const ll MAXN = 1e6 + 100;

#define int long long

vector<vector<int>> graph;
map<int,int> mp;
vector<int> A;
int N, v, mx_v, a, b, sz[MAXN], marked[MAXN];
int sum[MAXN], ans = 0;

int get_sz(int node, int parent) {
    sz[node] = 1;
    for (auto u : graph[node]) {
        if (u != parent && !marked[u])
            sz[node] += get_sz(u, node);
    }
    return sz[node];
}

int find_centro(int node, int parent, int n) {
    for (auto u : graph[node]) {
        if (u != parent && !marked[u] && sz[u] * 2 >= n)
            return find_centro(u, node, n);
    }
    return node;
}

void dfs(int node, int parent, int now, int rem, int len) {
    ans = max(ans, now - min(A[rem], A[node])); 
    if (len == v)
        return ;
    for (auto u : graph[node]) {
        if (u != parent && !marked[u])
            dfs(u, node, now + sum[u] - A[node], rem, len + 1);
    }
}

void get(int node, int parent, int now, int len) {
    for (int i = 2; i <= min(mx_v, v - len); i++)
        ans = max(ans, now + mp[i]);

    for (auto u : graph[node]) {
        if (u != parent && !marked[u])
            get(u, node, now + sum[u] - A[node], len + 1);
    }
}

void add(int node, int parent, int now, int len) {
    mp[len] = max(mp[len], now - A[node]);
    mx_v = max(mx_v, len);
    for (auto u : graph[node]) {
        if (u != parent && !marked[u])
            add(u, node, now + sum[u] - A[node], len + 1);
    }
}

void decompose(int node) {
    int n = get_sz(node, node);
    int centro = find_centro(node, node, n);

    marked[centro] = true;
    dfs(centro, centro, sum[centro] + A[centro], centro, 1);

    mp = map<int,int>();
    for (int i = 0; i <= 100; i++)
        mp[i] = -1e15;
    mx_v = 0;
    for (auto u : graph[centro]) {
        get(u, centro, sum[u] + A[u] - A[centro], 1);
        add(u, centro, sum[centro] + sum[u], 2);
    }

    mp = map<int,int>();
    for (int i = 0; i <= 100; i++)
        mp[i] = -1e15;
    mx_v = 0;
    reverse(graph[centro].begin(), graph[centro].end());
    for (auto u : graph[centro]) {
        get(u, centro, sum[u] + A[u] - A[centro], 1);
        add(u, centro, sum[centro] + sum[u], 2);
    }
}

signed main() {
    fast;
    cin >> N >> v;

    graph = vector<vector<int>>(N+1, vector<int>());
    A = vector<int>(N+1);
    for (int i = 1; i <= N; i++)
        cin >> A[i];
    for (int i = 1; i < N; i++) {
        cin >> a >> b;
        graph[a].push_back(b);
        graph[b].push_back(a);
    }
    for (int i = 1; i <= N; i++) {
        for (auto u : graph[i])
            sum[i] += A[u];
    }
    decompose(1);

    cout << ans << "\n";
}

• Subtask 1: 0 / 20
• Subtask 2: 0 / 20
• Subtask 3: 0 / 30
• Subtask 4: 0 / 30