图论专项shortest_paths：UVa 11280

来源：互联网发布：c语言游戏五子棋编辑：程序博客网时间：2024/05/16 11:50
增加一维记录走过的步数进行SPFA即可，最后注意从小到大更新结果。
#include <iostream>#include <cstdio>#include <queue>#include <cstring>#include <map>#include <string>#include <utility>using namespace std;typedef pair<int,int> pii;const int maxn=110;const int maxm=2000;const int inf=1<<30;map<string,int> name;int n,m,q,e;int head[maxn],pnt[maxm],nxt[maxm],cost[maxm];int d[maxn][maxn],vis[maxn][maxn];void addedge(int u,int v,int c){    pnt[e]=v;cost[e]=c;nxt[e]=head[u];head[u]=e++;}void bellmanford(){    for(int i=0;i<n;i++)        for(int j=0;j<n;j++)            d[i][j]=inf,vis[i][j]=0;    queue<pii> q;    int s=name["Calgary"];    q.push(make_pair(s,0));    d[s][0]=0;vis[s][0]=1;    while(!q.empty())    {        pii p=q.front();q.pop();        int u=p.first,ud=p.second;        vis[u][ud]=0;        for(int i=head[u];i!=-1;i=nxt[i])        {            int v=pnt[i],c=cost[i],vd=ud+1;            if(d[v][vd]>d[u][ud]+c)            {                d[v][vd]=d[u][ud]+c;                if(!vis[v][vd])                {                    vis[v][vd]=1;                    q.push(make_pair(v,vd));                }            }        }    }    for(int i=0;i<n;i++)        for(int j=1;j<n;j++)            d[i][j]=min(d[i][j],d[i][j-1]);}int main(){    int T,kase=1;    cin>>T;    while(T--)    {        cin>>n;        name.clear();        for(int i=0;i<n;i++)        {            string s;            cin>>s;            name[s]=i;        }        cin>>m;        memset(head,-1,sizeof(head));        e=0;        for(int i=0;i<m;i++)        {            string s1,s2;            int u,v,c;            cin>>s1>>s2>>c;            u=name[s1],v=name[s2];            addedge(u,v,c);        }        int t=name["Fredericton"];        bellmanford();        cin>>q;        cout<<"Scenario #"<<kase++<<endl;        while(q--)        {            int limit;            cin>>limit;            if(limit+1>=n) cout<<"Total cost of flight(s) is $"<<d[t][n-1]<<endl;            else if(d[t][limit+1]==inf) cout<<"No satisfactory flights"<<endl;            else cout<<"Total cost of flight(s) is $"<<d[t][limit+1]<<endl;        }        if(T) puts("");    }    return 0;}