Submission #35836

#	Time	Username	Problem	Language	Result	Execution time	Memory
35836		funcsr	Chase (CEOI17_chase)	C++14	100 / 100	493 ms	290376 KiB

chase

#include <cstdio>
#include <iostream>
#include <algorithm>
#include <string>
#include <cstring>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <cmath>
#include <iomanip>
#include <cassert>
#include <bitset>
using namespace std;

typedef pair<int, int> P;
#define rep(i, n) for (int i=0; i<(n); i++)
#define all(c) (c).begin(), (c).end()
#define uniq(c) c.erase(unique(all(c)), (c).end())
#define index(xs, x) (int)(lower_bound(all(xs), x) - xs.begin())
#define _1 first
#define _2 second
#define pb push_back
#define INF 1145141919
#define MOD 1000000007
inline void chmax(long long &x, long long v) { if (x < v) x = v; }

int N, K;
int A[100001];
long long T[100000];
vector<int> G[100000];

long long down[100000][101];
long long dp[100000][101][2];
int to[100000][101];

void f(int x, int p) {
  for (int t : G[x]) {
    if (t == p) continue;
    f(t, x);
    rep(k, K+1) chmax(down[x][k], down[t][k]);
    if (p != -1) rep(k, K) chmax(down[x][k+1], down[t][k]+T[x]-A[p]);
  }
}

inline void update(int x, int k, long long val, int t) {
  if (val > dp[x][k][0]) {
    if (t == to[x][k]) dp[x][k][0] = val;
    else {
      dp[x][k][1] = dp[x][k][0];
      dp[x][k][0] = val;
      to[x][k] = t;
    }
  }
  else if (val > dp[x][k][1]) {
    dp[x][k][1] = val;
  }
}

void g(int x, int p) {
  if (p != -1) {
    rep(k, K+1) {
      long long m = 0;
      int s = 0;
      if (to[p][k] == x) s++;
      update(x, k, dp[p][k][s], p);
      if (k < K) update(x, k+1, dp[p][k][s] + T[p] - A[x], p);
    }
  }
  for (int t : G[x]) {
    if (t == p) continue;
    rep(k, K+1) update(x, k, down[t][k], t);
  }

  for (int t : G[x]) {
    if (t == p) continue;
    g(t, x);
  }
}

signed main() {
  ios::sync_with_stdio(false); cin.tie(0);
  cin >> N >> K;
  if (K == 0) {
    cout << 0 << "\n";
    return 0;
  }
  rep(i, N) cin >> A[i];
  rep(i, N-1) {
    int u, v;
    cin >> u >> v;
    u--, v--;
    G[u].pb(v);
    G[v].pb(u);
  }
  rep(i, N) for (int t : G[i]) T[i] += A[t];
  rep(i, N) rep(j, K+1) to[i][j] = -1;

  f(0, -1);
  g(0, -1);
  long long m = 0;
  rep(i, N) {
    chmax(m, dp[i][K][0]);
    chmax(m, dp[i][K-1][0] + T[i]);
  }
  cout << m << "\n";
  return 0;
}

Compilation message (stderr)

chase.cpp: In function 'void g(int, int)':
chase.cpp:63:17: warning: unused variable 'm' [-Wunused-variable]
       long long m = 0;
                 ^

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