L3022 地铁一日游

floyd算法建立新图，dfs标记~

#include<bits/stdc++.h>
using namespace std;
const int maxn=1010;
const int inf=1e9;
int d[maxn][maxn];
vector<int> g[maxn];
bool visit[maxn];
bool isend[maxn];
int N,M,K;
void floyd () {
    for (int k=1;k<=N;k++)
    for (int i=1;i<=N;i++)
    for (int j=1;j<=N;j++)
    if (i!=j) d[i][j]=min(d[i][j],d[i][k]+d[k][j]);
} 
void dfs (int s) {
    visit[s]=true;
    for (int i=0;i<g[s].size();i++) {
        if (visit[g[s][i]]==false) {
            dfs (g[s][i]);
        }
    }
}
int main () {
    scanf ("%d %d %d",&N,&M,&K);
    int u,v,distance;
    for (int i=1;i<=N;i++)
    for (int j=1;j<=N;j++)
    d[i][j]=inf;
    for (int i=0;i<M;i++) {
        scanf ("%d",&u);
        isend[u]=true;
        while (1) {
            scanf ("%d %d",&distance,&v);
            d[u][v]=min(d[u][v],distance);
            d[v][u]=d[u][v];
            u=v;
            char ch=getchar ();
            if (ch=='\n') break;
        }
        isend[u]=true;
    }
    floyd ();
    for (int i=1;i<=N;i++) {
        unordered_map<int,int> pos;
        for (int j=1;j<=N;j++) {
            if (i!=j&&d[i][j]>pos[d[i][j]/K+2]&&d[i][j]!=inf) 
            pos[d[i][j]/K+2]=d[i][j];
        }
        for (int j=1;j<=N;j++) 
        if (i!=j) {
            if (d[i][j]==pos[d[i][j]/K+2]||(isend[j]==true&&d[i][j]!=inf)) 
            g[i].push_back(j);
        }
    }
    int q;
    scanf ("%d",&q);
    int s;
    for (int i=0;i<q;i++) {
        scanf ("%d",&s);
        fill (visit,visit+maxn,false);
        dfs (s);
        int flag=0;
        for (int j=1;j<=N;j++) {
            if (visit[j]==true) {
                if (flag!=0) printf (" ");
                printf ("%d",j);
                flag++;
            }
        }
        printf ("\n");
    }
    return 0;
}