Submission #738224

#	Time	Username	Problem	Language	Result	Execution time	Memory
738224		Ronin13	Roadside Advertisements (NOI17_roadsideadverts)	C++14	100 / 100	67 ms	14320 KiB

roadsideadverts

#include <bits/stdc++.h>
#define ll long long
#define f first
#define s second
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pb push_back
#define epb emplace_back
#define ull unsigned ll
using namespace std;
const int nmax = 200001;

vector <vector <pii> > g(nmax);
int in[nmax], out[nmax], timer = 0;
int p[nmax][20];
int d[nmax];

void dfs(int v, int e){
    in[v] = ++timer;
    p[v][0] = e;
    for(int j= 1; j < 20; j++)
        p[v][j] = p[p[v][j - 1]][j - 1];
    for(auto x : g[v]){
        int to = x.f, len = x.s;
        if(to == e) continue;
        d[to] = d[v] + len;
        dfs(to, v);
    }
    out[v] = ++timer;
}

bool ispar(int x, int y){
    return in[x] <= in[y] && out[x] >= out[y];
}

int lca(int u, int v){
    if(ispar(u, v))
        return u;
    if(ispar(v, u))
        return v;
    for(int j = 19; j >= 0; j--){
        if(ispar(p[v][j], u)) continue;
        v = p[v][j];
    }
    return p[v][0];
}

int dist(int a, int b){
    return d[a] + d[b] - 2 * d[lca(a, b)];
}

int solve(vector <int> vec){
    vector <pii> t;
    for(int to : vec)
        t.pb({in[to], to});
    sort(t.begin(), t.end());
    for(int j = 1; j< vec.size(); j++){
        int x = lca(t[j - 1].s, t[j].s);
        t.pb({in[x], x});
    }
    sort(t.begin(), t.end());
    int ans = 0;
    stack <int> st;
    st.push(t[0].s);
    for(int i = 1; i < t.size(); i++){
        while(!st.empty()){
            int x = st.top();
            if(out[x] < in[t[i].s]) st.pop();
            else break;
        }
        int x = st.top();
        ans += dist(x, t[i].s);
        st.push(t[i].s);
    }
    return ans;
}

int main(){
    ios_base::sync_with_stdio(false); cin.tie(0);
    int n; cin >> n;
    for(int i = 1; i < n; i++){
        int u, v; cin >> u >> v;
        int w; cin >> w;
        g[u].pb({v, w});
        g[v].pb({u, w});
    }
    dfs(0, 0);
    int q; cin >> q;
    while(q--){
        vector <int> x(5);
        for(int i = 0; i < 5; i++)
            cin >> x[i];
        cout << solve(x) << "\n";
    }
}

Compilation message (stderr)

roadsideadverts.cpp: In function 'int solve(std::vector<int>)':
roadsideadverts.cpp:57:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   57 |     for(int j = 1; j< vec.size(); j++){
      |                    ~^~~~~~~~~~~~
roadsideadverts.cpp:65:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   65 |     for(int i = 1; i < t.size(); i++){
      |                    ~~^~~~~~~~~~

• Subtask 1: 7 / 7
• Subtask 2: 23 / 23
• Subtask 3: 40 / 40
• Subtask 4: 30 / 30