Submission #110141

#	Time	Username	Problem	Language	Result	Execution time	Memory
110141		TAISA_	Beads and wires (APIO14_beads)	C++14	0 / 100	2 ms	384 KiB

beads

#include <bits/stdc++.h>
#define all(vec) vec.begin(), vec.end()
using namespace std;
using ll = long long;
using P = pair<ll, ll>;
constexpr ll INF = (1LL << 40) - 1LL;
constexpr ll LINF = (1LL << 60) - 1LL;
constexpr double eps = 1e-9;
constexpr ll MOD = 1000000007LL;
template <typename T>
bool chmin(T& a, T b) {
    if(a > b) {
        a = b;
        return true;
    }
    return false;
};
template <typename T>
bool chmax(T& a, T b) {
    if(a < b) {
        a = b;
        return true;
    }
    return false;
};
template <typename T>
ostream& operator<<(ostream& os, vector<T> v) {
    for(int i = 0; i < v.size(); i++) {
        os << v[i] << (i + 1 == v.size() ? "\n" : " ");
    }
    return os;
}
template <typename T>
vector<T> make_v(size_t a) {
    return vector<T>(a);
}
template <typename T, typename... Ts>
auto make_v(size_t a, Ts... ts) {
    return vector<decltype(make_v<T>(ts...))>(a, make_v<T>(ts...));
}
template <typename T, typename V>
typename enable_if<is_class<T>::value == 0>::type fill_v(T& t, const V& v) {
    t = v;
}
template <typename T, typename V>
typename enable_if<is_class<T>::value != 0>::type fill_v(T& t, const V& v) {
    for(auto& e : t) {
        fill_v(e, v);
    }
};
int n;
vector<vector<P>> G;
vector<vector<vector<ll>>> dp;
ll dfs(int i, int f, int p) {
    if(dp[i][f][0] != -1) {
        return max(dp[i][f][0], dp[i][f][1]);
    }
    ll sum = 0, m21 = -INF, m22 = -INF, m1 = -INF, m3 = 0;
    for(auto pe : G[i]) {
        int e = pe.first;
        ll c = pe.second;
        if(e == p) {
            continue;
        }
        dfs(e, 0, i);
        dfs(e, 1, i);
        dfs(e, 2, i);
        ll t = max(dp[e][1][0] + c, dp[e][0][0]);
        sum += t;
        chmax(m1, dp[e][2][1] + c - t);
        chmax(m3, dp[e][0][1] - t);
        if(m21 < dp[e][2][0] + c - t) {
            m22 = m21;
            m21 = dp[e][2][0] + c - t;
        } else if(m22 < dp[e][2][0] + c - t) {
            m22 = dp[e][2][0] + c - t;
        }
    }
    ll res = -LINF;
    sum += m3;
    if(f == 0) {
        dp[i][f][1] = max(sum + m21 + m22, sum + m21 + m1);
        chmax(res, sum);
    } else if(f == 1) {
        chmax(res, sum + max(m21, m1));
    } else {
        chmax(res, sum);
        dp[i][f][1] = max(sum + m21 + m22, sum + m21 + m1);
    }
    return dp[i][f][0] = res;
}
int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cin >> n;
    G.resize(n);
    dp.resize(n);
    for(int i = 0; i < n; i++) {
        dp[i].resize(3);
        for(int j = 0; j < 3; j++) {
            dp[i][j].resize(2, -1);
        }
    }
    for(int i = 0; i < n - 1; i++) {
        int u, v, c;
        cin >> u >> v >> c;
        --u;
        --v;
        G[u].push_back(P(v, c));
        G[v].push_back(P(u, c));
    }
    dfs(0, 0, -1);
    cout << max(dp[0][0][0], dp[0][0][1]) << endl;
}

• Subtask 1: 0 / 13
• Subtask 2: 0 / 15
• Subtask 3: 0 / 29
• Subtask 4: 0 / 43