Submission #305373

#	Time	Username	Problem	Language	Result	Execution time	Memory
305373		caoash	Untitled (POI11_dyn)	C++14	10 / 100	709 ms	16888 KiB

Main

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

using ll = long long;

using vi = vector<int>;
using vl = vector<ll>;
#define pb push_back
#define rsz resize
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()

using pi = pair<int,int>;
#define f first
#define s second
#define mp make_pair

const int MX = 200005;
const int MOD = (int) (1e9 + 7);
const ll INF = (ll) 1e18;

namespace output {
  void pr(int x) {
    cout << x;
  }
  void pr(long x) {
    cout << x;
  }
  void pr(ll x) {
    cout << x;
  }
  void pr(unsigned x) {
    cout << x;
  }
  void pr(unsigned long x) {
    cout << x;
  }
  void pr(unsigned long long x) {
    cout << x;
  }
  void pr(float x) {
    cout << x;
  }
  void pr(double x) {
    cout << x;
  }
  void pr(long double x) {
    cout << x;
  }
  void pr(char x) {
    cout << x;
  }
  void pr(const char * x) {
    cout << x;
  }
  void pr(const string & x) {
    cout << x;
  }
  void pr(bool x) {
    pr(x ? "true" : "false");
  }

  template < class T1, class T2 > void pr(const pair < T1, T2 > & x);
  template < class T > void pr(const T & x);

  template < class T, class...Ts > void pr(const T & t,
    const Ts & ...ts) {
    pr(t);
    pr(ts...);
  }
  template < class T1, class T2 > void pr(const pair < T1, T2 > & x) {
    pr("{", x.f, ", ", x.s, "}");
  }
  template < class T > void pr(const T & x) {
    pr("{"); // const iterator needed for vector<bool>
    bool fst = 1;
    for (const auto & a: x) pr(!fst ? ", " : "", a), fst = 0;
    pr("}");
  }

  void ps() {
    pr("\n");
  } // print w/ spaces
  template < class T, class...Ts > void ps(const T & t,
    const Ts & ...ts) {
    pr(t);
    if (sizeof...(ts)) pr(" ");
    ps(ts...);
  }

  void pc() {
    cout << "]" << endl;
  } // debug w/ commas
  template < class T, class...Ts > void pc(const T & t,
    const Ts & ...ts) {
    pr(t);
    if (sizeof...(ts)) pr(", ");
    pc(ts...);
  }
  #define dbg(x...) pr("[", #x, "] = ["), pc(x);
}

#ifdef LOCAL
using namespace output;
#endif
// REMOVE BEFORE SUBMITTING TO USACO

int n, m;
int d[MX];
vector<int> adj[MX];
int dp1[MX], dp2[MX];
int need = 0;

void dfs(int v, int p, int mid) {
    dp1[v] = -1;
    dp2[v] = INT_MAX;
    for (int to : adj[v]) {
        if (to != p) {
            dfs(to, v, mid);
            if (dp1[to] != -1) {
                dp1[v] = max(dp1[v], dp1[to] + 1);
            }
            dp2[v] = min(dp2[v], dp2[to] + 1);
        }
    }
    if (dp1[v] == -1 && d[v]) {
        if (dp2[v] > mid) {
            dp1[v] = 0;
        }
    }
    if (dp1[v] == mid) {
        dp2[v] = 0;
        dp1[v] = -1;
        ++need;
    }
    return;
}

bool solve(int mid) {
    dfs(0, -1, mid);    
    if (need > m) {
        return false;
    }
    return true;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin >> n >> m;
    int cnt = 0;
    for (int i = 0; i < n; i++) {
        cin >> d[i];
        cnt += d[i];
    }
    for (int i = 0; i < n - 1; i++) {
        int u, v; cin >> u >> v;
        u--, v--;
        adj[u].pb(v), adj[v].pb(u);
    }
    int lo = 1, hi = n;
    int ans = 0;
    while (lo <= hi) {
        int mid = (lo + hi) / 2;
        need = 0;
        if (solve(mid)) {
            hi = mid - 1;
            ans = mid;
        }
        else {
            lo = mid + 1;
        }
    }
    if (m >= cnt) {
        cout << 0 << '\n';
    }
    else {
        cout << ans << '\n';
    }
}

• Subtask 1: 0 / 10
• Subtask 2: 10 / 10
• Subtask 3: 0 / 10
• Subtask 4: 0 / 10
• Subtask 5: 0 / 10
• Subtask 6: 0 / 10
• Subtask 7: 0 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 10
• Subtask 10: 0 / 10