제출 #1348826

#제출 시각아이디문제언어결과실행 시간메모리
1348826hoangmc2009Evacuation plan (IZhO18_plan)C++17
100 / 100
299 ms63840 KiB
#include <bits/stdc++.h>
using namespace std;
using i64 = long long;
const int maxn=5e5+9;
int n,m,k,q,dist[maxn];
pair<int,int> E[maxn];
vector<pair<int,int>> adj[maxn],bdj[maxn];
set<pair<int,int>> st;
int dsu[maxn],par[20][maxn],mn[20][maxn],tin[maxn],tout[maxn];
int find_set(int u) {return dsu[u]<0?u:dsu[u]=find_set(dsu[u]);}
bool union_set(int u,int v)
{
    u=find_set(u); v=find_set(v);
    if(u==v) return false;
    if(dsu[u]>dsu[v]) swap(u,v);
    dsu[u]+=dsu[v]; dsu[v]=u;
    return true;
}
int main()
{
    if(fopen("D:/CPP/THEMIS/test.inp","r"))
    {
        freopen("D:/CPP/THEMIS/test.inp","r",stdin);
        freopen("D:/CPP/THEMIS/test.out","w",stdout);
    }
    ios_base::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);
    cin>>n>>m;
    for(int u,v,w,i=1;i<=m;++i)
    {
        cin>>u>>v>>w; E[i]={u,v};
        adj[u].push_back({v,w});
        adj[v].push_back({u,w});
    }
    memset(dist,0x3F,sizeof(dist));
    cin>>k;
    for(int u,i=1;i<=k;++i)
    {
        cin>>u;
        dist[u]=0;
        st.insert({0,u});
    }
    while(!st.empty())
    {
        int u=st.begin()->second;
        st.erase(st.begin());
        for(auto& [v,w]:adj[u])
        {
            if(dist[v]>dist[u]+w)
            {
                st.erase({dist[v],v});
                dist[v]=dist[u]+w;
                st.insert({dist[v],v});
            }
        }
    }
    sort(E+1,E+m+1,[&](pair<int,int> x,pair<int,int> y){
        return min(dist[x.first],dist[x.second])>min(dist[y.first],dist[y.second]);
    });
    fill(dsu,dsu+n+1,-1);
    for(int i=1;i<=m;++i)
    {
        auto [u,v]=E[i];
        if(union_set(u,v))
        {
            bdj[u].push_back({v,min(dist[u],dist[v])});
            bdj[v].push_back({u,min(dist[u],dist[v])});
        }
    }
    int timer=0;
    auto DFS=[&](auto&& self,int u,int pu)->void
    {
        par[0][u]=pu; tin[u]=++timer;
        for(auto& [v,w]:bdj[u])
            if(v!=pu) self(self,v,u),mn[0][v]=w;
        tout[u]=timer;
    };
    DFS(DFS,1,0); par[0][1]=1; mn[0][1]=2e9;
    for(int i=1;i<20;++i)
    {
        for(int j=1;j<=n;++j)
        {
            par[i][j]=par[i-1][par[i-1][j]];
            mn[i][j]=min(mn[i-1][j],mn[i-1][par[i-1][j]]);
        }
    }
    auto isA=[&](int u,int v)->bool {
        return tin[u]<=tin[v] and tout[v]<=tout[u];
    };
    auto get=[&](int u,int v)->int
    {
        int res=2e9;
        if(isA(v,u)) swap(u,v);
        for(int i=19;i>=0;--i)
        {
            if(!isA(par[i][u],v))
            {
                res=min(res,mn[i][u]);
                u=par[i][u];
            }
        }
        if(!isA(u,v)) res=min(res,mn[0][u]),u=par[0][u];
        for(int i=19;i>=0;--i)
        {
            if(isA(u,par[i][v]) and par[i][v]!=u)
            {
                res=min(res,mn[i][v]);
                v=par[i][v];
            }
        }
        return min(res,mn[0][v]);
    };
    cin>>q;
    for(int u,v;q>0;--q)
    {
        cin>>u>>v;
        cout<<get(u,v)<<"\n";
    }
}

컴파일 시 표준 에러 (stderr) 메시지

plan.cpp: In function 'int main()':
plan.cpp:23:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   23 |         freopen("D:/CPP/THEMIS/test.inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
plan.cpp:24:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   24 |         freopen("D:/CPP/THEMIS/test.out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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