Submission #448348

#	Time	Username	Problem	Language	Result	Execution time	Memory
448348		ak2006	Evacuation plan (IZhO18_plan)	C++14	100 / 100	1959 ms	175008 KiB

plan

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vb = vector<bool>;
using vvb = vector<vb>;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vl = vector<ll>;
using vvl = vector<vl>;
using vvvl = vector<vvl>;
const int inf = 1e9;
#define pb push_back
#define fast ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
void setIO()
{
    fast;
}
int RET = inf;
struct DSU
{
    vi p,sz;
    int n;
    DSU(int _n)
    {
        n = _n;
        p.assign(n + 1,-1);
        sz.assign(n + 1,1);
        for (int i = 0;i<=n;i++)p[i] = i;
    }
    int Find(int a)
    {
        if (p[a] == a)return a;
        return p[a] = Find(p[a]);
    }
    void Unite(int a,int b)
    {
         a = Find(a),b = Find(b);
         if (a == b)return;
         if (sz[a] < sz[b])swap(a,b);
         p[b] = a;
         sz[b] += sz[a];
    }
};
int n = 1e5 + 5,TIMER = 1;
vvvi adj(n),graph(n);
vi in(n),out(n),dist(n,inf);
vvi anc(n,vi(21)),dp(n,vi(21,inf)),edges,tree;

void dfs(int u,int p,ll w)
{
    in[u] = TIMER++;
    anc[u][0] = p;
    dp[u][0] = w;
    for (int i = 1;i<=20;i++){
        anc[u][i] = anc[anc[u][i - 1]][i - 1];
        dp[u][i] = min(dp[u][i - 1],dp[anc[u][i - 1]][i - 1]);
    }
    for (auto val:graph[u]){
        int v = val[0],wt = val[1];
        if (v == p)continue;
        dfs(v,u,wt);
    }
    out[u] = TIMER++;
}
bool is_ancestor(int u,int v)
{
    return in[u] <= in[v] && out[u] >= out[v];
}
int LCA(int u,int v)
{
    if (is_ancestor(u,v))return u;
    for (int i = 20;i>=0;i--)
        if (!is_ancestor(anc[u][i],v)){
            RET = min(RET,dp[u][i]);
            u = anc[u][i];
        }
    RET = min(RET,dp[u][0]);
    return anc[u][0];
}
void query(int u,int v)
{
    if (u == v)return;
    for (int i = 20;i>=0;i--){
        if (!is_ancestor(anc[u][i],v)){
            RET = min(RET,dp[u][i]),u = anc[u][i];
        }
    }
    RET = min(RET,dp[u][0]);
}
int main()
{
    setIO();
    int n,m,q,k;
    cin>>n>>m;
    priority_queue<pair<int,int>>qe;
    while (m--){
        int u,v,w;
        cin>>u>>v>>w;
        adj[u].pb({v,w}),adj[v].pb({u,w});
        edges.pb({u,v});
    }
    cin>>k;
    while (k--){
        int u;
        cin>>u;
        dist[u] = 0;
        qe.push({0,u});
    }
    while (!qe.empty()){
        int u = qe.top().second;
        int d = -qe.top().first;
        qe.pop();
        if (dist[u] != d)continue;
        for (auto val:adj[u]){
            int v = val[0];
            int w = val[1];
            if (dist[v] > dist[u] + w){
                dist[v] = dist[u] + w;
                qe.push({-dist[v],v});
            }
        }
    }
    for (auto e:edges){
        int u = e[0],v = e[1],w = min(dist[u],dist[v]);
        tree.pb({w,u,v});
    }
    sort(tree.rbegin(),tree.rend());
    DSU val(n);
    for (auto it:tree){
        int u = it[1],v = it[2],w = it[0];
        if (val.Find(u) == val.Find(v))continue;
        val.Unite(u,v);
        graph[u].pb({v,w});
        graph[v].pb({u,w});
    }
    dfs(1,1,inf);
    cin>>q;
    while (q--){
        int u,v;
        cin>>u>>v;
        if (in[u] > in[v])swap(u,v);
        RET = inf;
        int l = LCA(u,v);
        query(v,l);
        cout<<RET<<endl;
    }
    return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 13 / 13
• Subtask 3: 12 / 12
• Subtask 4: 19 / 19
• Subtask 5: 46 / 46