Submission #1020562

#	Time	Username	Problem	Language	Result	Execution time	Memory
1020562		vjudge1	Flood (IOI07_flood)	C++17	73 / 100	203 ms	40948 KiB

flood

#include<bits/stdc++.h>
using namespace std;
int X[100100],Y[100100],vis[400100],lev[400100],side[100100][4][2],Xof[400100];
vector<pair<int,bool>> adj[400100];
void AE(int a,int b,int c){
    adj[a].push_back({b,c});
    adj[b].push_back({a,c});
}
set<pair<int,int>>st;
int main(){
    cin.tie(0)->sync_with_stdio(0);
    int n,w;
    cin>>n;
    for(int i=1;i<=n;i++)
        cin>>X[i]>>Y[i];
    cin>>w;
    for(int i=1;i<=w;i++){
        int a,b;
        cin>>a>>b;
        if(X[a]==X[b]){
            if(Y[a]>Y[b])swap(a,b);
            side[a][2][1]=i;
            side[a][2][0]=i+w;
            side[b][0][0]=i;
            side[b][0][1]=i+w;
            Xof[i]=X[a];
            st.insert({Xof[i],i});
        } else {
            if(X[a]>X[b])swap(a,b);
            side[a][1][0]=i;
            side[a][1][1]=i+w;
            side[b][3][1]=i;
            side[b][3][0]=i+w;
            Xof[i]=1e9;
        }
        AE(i,i+w,1);
    }
    for(int i=1;i<=n;i++)
        for(int j=0;j<4;j++) if(side[i][j][1])
            for(int k=(j+1)%4;;k=(k+1)%4) if(side[i][k][0]){
                AE(side[i][k][0],side[i][j][1],0);break;}
    deque<int>Q;
    memset(lev,7,sizeof lev);
    while(1){
        if(st.empty())break;
        int K=st.begin()->second;
        Q.push_back(K);
        lev[K]=0;
        while(Q.size()){
            int x=Q.front();Q.pop_front();
            if(vis[x])continue;
            if(x<=w)st.erase({Xof[x],x});
            vis[x]=1;
            for(auto[i,j]:adj[x])
                if(lev[i]>lev[x]+j) if(j)
                    Q.push_back(i),lev[i]=lev[x]+1;
                else Q.push_front(i),lev[i]=lev[x];
        }
    }
    vector<int>v;
    for(int i=1;i<=w;i++)
        if(lev[i]==lev[i+w])
            v.push_back(i);
    cout<<v.size()<<'\n';
    for(auto i:v)
        cout<<i<<'\n';
}

Compilation message (stderr)

flood.cpp: In function 'int main()':
flood.cpp:55:19: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
   55 |                 if(lev[i]>lev[x]+j) if(j)
      |                   ^

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 3 / 3
• Subtask 5: 10 / 10
• Subtask 6: 3 / 3
• Subtask 7: 3 / 3
• Subtask 8: 3 / 3
• Subtask 9: 3 / 3
• Subtask 10: 9 / 9
• Subtask 11: 9 / 9
• Subtask 12: 0 / 9
• Subtask 13: 0 / 9
• Subtask 14: 0 / 9