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#include <iostream> #include <cstdio> #include <sstream> #include <vector> #include <string> #include <cstring> #include <queue> using namespace std; vector<int> vb[305]; vector<int> par; bool bfs(int path[],int st,int ed) { int visit[400]; for(int i=0;i<400;i++) visit[i]=0; queue<int> q; q.push(st); visit[st]=1; int a,b; if(st==ed) return 1; while(!q.empty()) { a = q.front();q.pop(); if(a==ed) return 1; for(int i=0;i<vb[a].size();i++) { b = vb[a][i]; if(visit[b]==0) { visit[b]=1; q.push(b); path[b]=a; } } } return 0; } int main() { int router,qry; int fr,to,st,ed,i; string str; while(scanf("%d",&router)!=EOF) { getchar(); for(int II=0;II<305;II++) vb[II].clear(); for(int II=0;II<router;II++) { getline(cin,str); i=0; fr=0; while(str[i]!='-') { fr *= 10;fr += (str[i++]-'0'); } i+=1; to=0; while(i<str.size()) { if(str[i]==',') { vb[fr].push_back(to); to=0; i+=1; } else { to *= 10; to += (str[i++]-'0'); } } vb[fr].push_back(to); } scanf("%d",&qry); for(int II=0;II<qry;II++) { scanf("%d%d",&st,&ed); int *path = new int[router+5]; for(int JJ=0;JJ<router+5;JJ++) path[JJ]=JJ; bool f = bfs(path,st,ed); if(II==0) printf("-----\n"); if(!f) printf("connection impossible\n"); else { //cout<<"path = "<<path[5]<<"\n"; int cc = ed; par.clear(); while(path[cc]!=cc) { par.push_back(cc); cc=path[cc]; } par.push_back(cc); for(int LL=par.size()-1;LL>=0;LL--) printf("%d%s",par[LL],LL==0?"\n":" "); } delete path; } } return 0; } |
There is another solution using Linked List in case Router ID is not limited from 1 to 300. But for this problem this solution gets TLE.
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#include <iostream> #include <cstdio> #include <sstream> #include <vector> #include <string> #include <cstring> #include <queue> using namespace std; struct Node{ int number; Node *next; }; struct Edge{ int from,to; Edge *next; Edge(int f,int t); }; Node *nodeList=0; Edge *edgeList=0; int IndexOfId[400]; vector<int> vb[400]; vector<int> par; int GetNodeIndex(int num) { Node *p=nodeList; int idx=0; while(p->next) { p=p->next; if(p->number==num) return idx; idx+=1; } p->next=new Node(); p=p->next; p->number=num; p->next=0; IndexOfId[idx]=num; return idx; } Edge::Edge(int f,int t) { from = f; to = t; } void init() { Node *p=nodeList,*q; memset(IndexOfId,0,sizeof(IndexOfId)); while(p) { q = p; p = p->next; delete q; } nodeList = new Node(); nodeList->next=0; nodeList->number=-100; Edge *pp=edgeList,*tmp; while(pp) { tmp=pp; pp=pp->next; delete tmp; } } int CountNode() { Node *p=nodeList->next; int cnt=0; while(p) { cnt+=1; p=p->next; } return cnt; } bool bfs(int path[],int st,int ed) { int visit[400]; for(int i=0;i<400;i++) visit[i]=0; queue<int> q; q.push(st); visit[st]=1; int a,b; if(st==ed) return 1; while(!q.empty()) { a = q.front();q.pop(); if(a==ed) return 1; for(int i=0;i<vb[a].size();i++) { b = vb[a][i]; if(visit[b]==0) { visit[b]=1; q.push(b); path[b]=a; } } } return 0; } int main() { int n,m,fr,to,i; int a,b; string str; while(scanf("%d",&n)!=EOF) { getchar(); init(); for(int II=0;II<n;II++) { getline(cin,str); i=0; fr=0; while(str[i]!='-') { fr *= 10;fr += (str[i++]-'0'); } fr = GetNodeIndex(fr); to=0; i+=1; while(i<str.size()) { if(str[i]==',') { to = GetNodeIndex(to); Edge *e=new Edge(fr,to); e->next = edgeList; edgeList = e; to=0; i+=1; } else { to *= 10; to += (str[i++]-'0'); } } to = GetNodeIndex(to); Edge *e=new Edge(fr,to); e->next = edgeList; edgeList = e; } int nodeCount = CountNode(); for(int II=0;II<400;II++) vb[II].clear(); Edge *tmpEdge=edgeList; while(tmpEdge) { a = tmpEdge->from; b = tmpEdge->to; vb[a].push_back(b); tmpEdge=tmpEdge->next; } scanf("%d",&m); for(int II=0;II<m;II++) { int st,ed; scanf("%d%d",&st,&ed); st=GetNodeIndex(st); ed=GetNodeIndex(ed); int *path = new int[nodeCount]; for(int KK=0;KK<nodeCount;KK++) path[KK]=KK; bool f = bfs(path,st,ed); if(II==0) printf("-----\n"); if(!f) printf("connection impossible\n"); else { int cc = ed; par.clear(); while(path[cc]!=cc) { par.push_back(cc); cc=path[cc]; } par.push_back(cc); for(int LL=par.size()-1;LL>=0;LL--) printf("%d%s",IndexOfId[par[LL]],LL==0?"\n":" "); } delete path; } } return 0; } |