78 lines
1.7 KiB
C++
78 lines
1.7 KiB
C++
#include <iostream>
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#include <stdio.h>
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#include <string.h>
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#include <algorithm>
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#include <map>
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#include <math.h>
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#include <queue>
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#include <vector>
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#include<string>
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using namespace std;
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const int MAXN=1010;
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const int INF=0x3f3f3f3f;
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int dis[MAXN][MAXN];
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bool used[MAXN];
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vector<int>vec[MAXN];
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queue<int>que;
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void bfs(int i)
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{
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memset(used,false,sizeof(used));
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dis[i][i]=0;
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used[i]=true;
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que.push(i);
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while(!que.empty())
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{
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int t=que.front();
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que.pop();
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int m=vec[t].size();
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for(int j=0;j<m;j++)
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{
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int v=vec[t][j];
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if(used[v])continue;
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if(dis[i][v]>dis[i][t]+1)
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dis[i][v]=dis[i][t]+1;
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que.push(v);
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used[v]=true;
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}
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}
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}
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map<string,int>mp;
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int main() {
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string str;
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string str2;
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int n,m,i,j;
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while(scanf("%d",&n)==1 && n)
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{
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mp.clear();
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for(i=0;i<n;i++)
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{
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cin>>str;
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mp[str]=i;
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}
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for(i=0;i<n;i++)
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{
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dis[i][i]=0;
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for(j=i+1;j<n;j++)
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dis[i][j]=dis[j][i]=INF;
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}
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scanf("%d",&m);
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for(i=0;i<n;i++)vec[i].clear();
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while(m--)
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{
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cin>>str>>str2;
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int t1=mp[str];
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int t2=mp[str2];
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vec[t1].push_back(t2);
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vec[t2].push_back(t1);
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}
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for(i=0;i<n;i++)bfs(i);
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int ans=0;
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for(i=0;i<n;i++)
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for(j=i+1;j<n;j++)
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ans=ans>dis[i][j]?ans:dis[i][j];
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if(ans==INF)ans=-1;
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printf("%d\n",ans);
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}
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return 0;
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}
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