Submission #1119753

#	Time	Username	Problem	Language	Result	Execution time	Memory
1119753		luvna	Election Campaign (JOI15_election_campaign)	C++14	10 / 100	170 ms	41548 KiB

election_campaign

#include<bits/stdc++.h>

#define MASK(i) (1 << (i))
#define pub push_back
#define all(v) v.begin(), v.end()
#define compact(v) v.erase(unique(all(v)), end(v))
#define pii pair<int,int>
#define fi first
#define se second
#define endl "\n"
#define sz(v) (int)(v).size()
#define dbg(x) "[" #x " = " << (x) << "]"

using namespace std;

template<class T> bool minimize(T& a, T b){if(a > b) return a = b, true;return false;}
template<class T> bool maximize(T& a, T b){if(a < b) return a = b, true;return false;}

typedef long long ll;
typedef long double ld;

mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rand(ll l, ll r){return uniform_int_distribution<ll>(l, r)(rng);}

const int N = 1e5 + 15;
const int lg = 17;

struct node{
    int u, v, w;
};

void solve(){
    int n; cin >> n;

    vector<vector<int>> g(n + 15);

    for(int i = 1; i < n; i++){
        int u, v; cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }

    vector<vector<int>> par(n + 15, vector<int>(lg+2,0));
    vector<int> h(n + 15);

    auto dfs = [&](auto& dfs, int u, int p) -> void{
        for(int v : g[u]) if(v != p){
            h[v] = h[u] + 1;
            par[v][0] = u;
            for(int j = 1; j <= lg; j++) par[v][j] = par[par[v][j-1]][j-1];
            dfs(dfs,v,u);
        }
    };

    auto lca = [&](int u, int v) -> int{
        if(h[v] > h[u]) swap(u,v);

        for(int j = lg; j >= 0; j--) if(h[u] - (1 << j) >= h[v]){
            u = par[u][j];
        }

        if(u == v) return u;

        for(int j = lg; j >= 0; j--){
            if(par[u][j] != par[v][j]){
                u = par[u][j];
                v = par[v][j];
            }
        }

        return par[u][0];
    };

    auto bin_lift = [&](int u, int v) -> int{
        for(int j = lg; j >= 0; j--) if(h[v] - (1 << j) > h[u]){
            v = par[v][j];
        }
        return v;
    };

    dfs(dfs,1,-1);

    int m; cin >> m;

    vector<vector<node>> evt(n + 15);

    while(m--){
        int u, v, w; cin >> u >> v >> w;
        //cout << u << " " << v << "  " << lca(u,v) << endl;
        evt[lca(u,v)].push_back({u,v,w});
    }

    vector<vector<int>> dp(n + 15, vector<int>(3));

    //dp[u][0] -> not pick u
    //dp[u][1] -> pick u

    //dp[u][0] = sum all max(dp[v][0], dp[v][1])

    auto dfsDP = [&](auto& dfsDP, int u, int p) -> void{
        int sum = 0;
        for(int v : g[u]) if(v != p){
            dfsDP(dfsDP,v,u);
            sum += max(dp[v][0], dp[v][1]);
        }
        dp[u][0] = dp[u][1] = sum;
        //if(!evt[u].empty()) cout << "case: " << dbg(u) << endl;
        for(auto &[U, V, w] : evt[u]){
            int ncost = sum + w;
            int fakeU = bin_lift(u,U);
            int fakeV = bin_lift(u,V);
            //cout << "--------" << endl;
            //cout << dbg(U) << dbg(fakeU) << endl;
            //cout << dbg(V) << dbg(fakeV) << endl;
            if(u != fakeU){
                ncost -= max(dp[fakeU][0], dp[fakeU][1]);
                ncost += dp[U][0];
            }
            if(u != fakeV){
                ncost -= max(dp[fakeV][0], dp[fakeV][1]);
                ncost += dp[V][0];
            }
            maximize(dp[u][1], ncost);
        }
    };

    dfsDP(dfsDP,1,-1);

    cout << max(dp[1][0], dp[1][1]);
}

signed main(){
    ios_base::sync_with_stdio(NULL);
    cin.tie(0); cout.tie(0);

    #define task "task"

    if(fopen(task".INP", "r")){
        freopen(task".INP", "r", stdin);
        freopen(task".OUT", "w", stdout);
    }

    int t; t = 1; //cin >> t;
    while(t--) solve();
}

Compilation message (stderr)

election_campaign.cpp: In lambda function:
election_campaign.cpp:108:19: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
  108 |         for(auto &[U, V, w] : evt[u]){
      |                   ^
election_campaign.cpp: In function 'int main()':
election_campaign.cpp:139:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  139 |         freopen(task".INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
election_campaign.cpp:140:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  140 |         freopen(task".OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 10
• Subtask 2: 5 / 5
• Subtask 3: 5 / 5
• Subtask 4: 0 / 30
• Subtask 5: 0 / 10
• Subtask 6: 0 / 40