제출 #448336

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
448336		ak2006	Evacuation plan (IZhO18_plan)	C++14	0 / 100	653 ms	99820 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 ll mod = 1e9 + 7,inf = 1e9;
#define pb push_back
#define fast ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
void setIO()
{
    fast;
    // #ifndef ONLINE_JUDGE
    // freopen("input.txt","r",stdin);
    // freopen("output.txt","w",stdout);
    // #endif
}
struct DSU
{
    int n;
    vi p;
    DSU(int _n)
    {
        n = _n;
        p.assign(n + 1,0);
        for (int i = 1;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 (b != a)
            p[b] = a;
    }
};
int n = 1e5 + 5,TIMER = 1;
vvvl adj(n),graph(n);
vi in(n),out(n);
vvi anc(n,vi(21));
vvl dp(n,vl(21,inf));
vl dist(n,inf);
vvi edges;
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];
        if (v == p)continue;
        dfs(v,u,val[1]);
    }
    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 (in[u] > in[v])swap(u,v);
    if (is_ancestor(u,v))return u;
    for (int i = 20;i>=0;i--){
        if (!is_ancestor(u,anc[v][i]))v = anc[v][i];
    }
    return anc[v][0];
}
ll minOnPath(int u,int lca)
{
    ll ret = inf;
    for (int i = 20;i>=0;i--){
        if (!is_ancestor(lca,anc[u][i])){
            ret = min(ret,dp[u][i]);
            u = anc[u][i];
        }
    }
    return min(ret,dp[u][0]);
}
int main()
{
    setIO();
    int n,m,q,k;
    cin>>n>>m;
    priority_queue<pair<ll,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;
        ll d = -qe.top().first;
        qe.pop();
        if (dist[u] != d)continue;
        for (auto val:adj[u]){
            int v = val[0];
            ll w = val[1];
            if (dist[v] > dist[u] + w){
                dist[v] = dist[u] + w;
                qe.push({-dist[v],v});
            }
        }
    }
    vvl tree;
    for (auto e:edges){
        int u = e[0],v = e[1];
        ll 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];
        ll 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;
        int lca = LCA(u,v);
        cout<<min(minOnPath(u,lca),minOnPath(v,lca))<<endl;
    }
    return 0;
}

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