Submission #902720

#	Time	Username	Problem	Language	Result	Execution time	Memory
902720		joelgun14	Chase (CEOI17_chase)	C++17	0 / 100	138 ms	62324 KiB

chase

// header file
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
// pragma
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
// macros
#define endl "\n"
#define ll long long
#define mp make_pair
#define ins insert
#define lb lower_bound
#define pb push_back
#define ub upper_bound
#define lll __int128
#define fi first
#define se second
using namespace std;
using namespace __gnu_pbds;
typedef tree<int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_multiset;
typedef tree<int, null_type, less<int>, rb_tree_tag,tree_order_statistics_node_update> ordered_set;
const int lim = 1e5 + 5, lim2 = 1e2 + 5;
// path rooted at index nd, with v breadcrumbs used
vector<int> edges[lim];
bool vis[lim];
ll res, sub[lim], dp[lim][lim2], v, par[lim], a[lim];
void dfs(int nd) {
  vis[nd] = 1;
  // take
  ll sum_child = 0;
  vector<int> child;
  for(auto i : edges[nd]) {
    if(!vis[i]) {
      par[i] = nd;
      dfs(i);
      sub[nd] += a[i];
      child.pb(i);
    }
  }
  ll prmx[v + 1], prmx2[v + 1];
  memset(prmx, 0, sizeof(prmx));
  memset(prmx2, 0, sizeof(prmx2));
  for(auto i : child) {
      // transition
      for(int j = 0; j <= v; ++j) {
        // case current is root and combine 2 paths (with root not taken)
        res = max(res, dp[i][j] + prmx[v - j]);
        // case current is root and combine 2 paths (with root taken)
        res = max(res, dp[i][j] + sub[nd] + a[par[nd]] + prmx2[v - j] - a[i]);
        if(j != 0)
          dp[nd][j] = max(dp[nd][j], dp[nd][j - 1]);
        // not take
        dp[nd][j] = max(dp[nd][j], dp[i][j]);
        // take
        if(j != 0)
          dp[nd][j] = max(dp[nd][j], dp[i][j - 1] + sub[nd] - a[i]);
        // case current is root and only single path (not combin of 2 paths)
        res = max(res, dp[nd][j]);
        // case current is root, only single path, and taken
        if(j != 0)
          res = max(res, dp[nd][j - 1] + sub[nd] + a[par[nd]] - a[i]);
      }
      for(int j = 1; j <= v; ++j) {
        prmx[j] = max(prmx[j], dp[i][j]);
        prmx2[j] = max(prmx2[j], dp[i][j] - a[i]);
      }
  }
}
int main() {
    ios_base::sync_with_stdio(0); cin.tie(NULL);
    int n;
    cin >> n >> v;
    for(int i = 1; i <= n; ++i)
      cin >> a[i];
    for(int i = 1; i < n; ++i) {
      int a, b;
      cin >> a >> b;
      edges[a].pb(b);
      edges[b].pb(a);
    }
    dfs(1);
    cout << res << endl;
    return 0;
}

Compilation message (stderr)

chase.cpp: In function 'void dfs(int)':
chase.cpp:31:6: warning: unused variable 'sum_child' [-Wunused-variable]
   31 |   ll sum_child = 0;
      |      ^~~~~~~~~

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