98 lines
1.6 KiB
C++
98 lines
1.6 KiB
C++
#include <stdio.h>
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#include <string.h>
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#include <algorithm>
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using namespace std;
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const int maxn=110;
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char s[maxn][maxn];
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int visit[maxn];
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int n;
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int len[maxn];
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int ans[maxn];
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int en[maxn],fa[maxn];
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int solve(int dep,int num)
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{
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if (en[dep]!=0) return en[dep]-1;
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visit[dep]=num;
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for(int i=0;i<len[dep];i++)
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{
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ans[dep]=i;
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int t=s[dep][i]-'a';
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if (visit[t])
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{
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int maxs=0;
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int counts=0;
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for(int j=0;j<n;j++)
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if (visit[j]>=visit[t])
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{
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if (ans[j]>0) return 1;
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if (len[j]>maxs) maxs=len[j];
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counts++;
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}
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if (counts>1) return 2;
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if (maxs>1) return 1;
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return 0;
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}
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int now=solve(t,num+1);
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if (now==0) continue;
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return now;
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}
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visit[dep]=0;
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return 0;
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}
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int find_fa(int u)
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{
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if (fa[u]!=u) fa[u]=find_fa(fa[u]);
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return fa[u];
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}
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int main()
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{
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int cas;
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scanf("%d",&cas);
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while(cas--)
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{
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scanf("%d",&n);
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for(int i=0;i<n;i++)
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{
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scanf("%s",s[i]);
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len[i]=strlen(s[i]);
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}
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memset(en,0,sizeof(en));
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for(int i=0;i<n;i++) fa[i]=i;
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for(int i=0;i<n;i++)
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{
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int have=0;
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for(int j=0;j<n;j++)
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{
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if (en[j]!=0) continue;
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bool flag=1;
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for(int k=1;k<len[j];k++)
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if (find_fa(s[j][0]-'a')!=find_fa(s[j][k]-'a')) flag=0;
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if (flag)
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{
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int t1=find_fa(j);
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int t2=find_fa(s[j][0]-'a');
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if (t1!=t2)
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{
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if (en[t2]==0) continue;
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if (len[t2]==1) en[t1]=1;
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else en[t1]=2;
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fa[t1]=t2;
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have++;
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} else
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{
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if (len[t2]==1) en[t1]=1;
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else en[t1]=2;
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have++;
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}
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}
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}
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if (have==0) break;
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}
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memset(visit,0,sizeof(visit));
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memset(ans,-1,sizeof(ans));
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int ans=solve(0,1);
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if (ans==2) puts("NO");
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else puts("YES");
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}
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}
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