Submission #483090

#	Time	Username	Problem	Language	Result	Execution time	Memory
483090		ntabc05101	Chase (CEOI17_chase)	C++17	100 / 100	342 ms	218700 KiB

chase

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

const int mxN = 100005;
const int mxV = 105;

int n, v;
long long P[mxN];
long long dp[mxN][mxV][2];
vector<int> adj[mxN];
long long sum[mxN];
long long res = 0;

void dfs(int u, int p = 0) {
  for (auto &to: adj[u]) {
    if (to != p) {
      dfs(to, u);
      for (int i = 1; i <= v; i++) {
        /*dp[u][i][1] = max(dp[u][i][1], max(dp[to][i][0], dp[to][i - 1][0] + sum[to] - P[u]));
        if (dp[u][i][1] > dp[u][i][0]) {
          swap(dp[u][i][1], dp[u][i][0]);
        }*/
        long long val = max(dp[to][i][0], dp[to][i - 1][0] + sum[to] - P[u]);
        if (val > dp[u][i][0]) {
          dp[u][i][1] = dp[u][i][0]; dp[u][i][0] = val;
        }
        else {
          if (val > dp[u][i][1]) {
            dp[u][i][1] = val;
          }
        }
      }
    }
  }
}

void dfs2(int u, int p = 0) {
  for (int i = 1; i <= v; i++) {
    res = max(res, max(dp[u][i][0], dp[u][i - 1][0] + sum[u]));
  }
  for (auto &to: adj[u]) {
    if (to != p) {
      long long tmp[v + 1];
      for (int i = 1; i <= v; i++) {
        tmp[i] = dp[u][i][0];
        if (max(dp[to][i][0], dp[to][i - 1][0] + sum[to] - P[u]) == dp[u][i][0]) {
          dp[u][i][0] = dp[u][i][1];
        }
      }
      for (int i = 1; i <= v; i++) {
        /*dp[to][i][1] = max(dp[to][i][1], max(dp[u][i][0], dp[u][i - 1][0] + sum[u] - P[to]));
        if (dp[to][i][1] > dp[to][i][0]) {
          swap(dp[to][i][1], dp[to][i][0]);
        }*/
        long long val = max(dp[u][i][0], dp[u][i - 1][0] + sum[u] - P[to]);
        if (val > dp[to][i][0]) {
          dp[to][i][1] = dp[to][i][0]; dp[to][i][0] = val;
        }
        else {
          if (val > dp[to][i][1]) {
            dp[to][i][1] = val;
          }
        }
      }
      dfs2(to, u);
      for (int i = 1; i <= v; i++) {
        dp[u][i][0] = tmp[i];
      }
    }
  }
}

int main() {
  if (fopen("input.txt", "r")) {
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
  }

  cin.tie(0)->sync_with_stdio(0);

  cin >> n >> v;
  for (int i = 1; i <= n; i++) {
    cin >> P[i];
  }
  for (int i = 0, x, y; i < n - 1; i++) {
    cin >> x >> y;
    adj[x].push_back(y);
    adj[y].push_back(x);
  }

  for (int i = 1; i <= n; i++) {
    for (auto &to: adj[i]) {
      sum[i] += P[to];
    }
  }
  dfs(1); dfs2(1);

  cout << res << "\n";

  return 0;
}

Compilation message (stderr)

chase.cpp: In function 'int main()':
chase.cpp:75:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   75 |     freopen("input.txt", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
chase.cpp:76:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   76 |     freopen("output.txt", "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

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