81 lines
1.6 KiB
C++
81 lines
1.6 KiB
C++
#include <stdio.h>
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#include <string.h>
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#include <queue>
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using namespace std;
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struct Node
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{
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int v;
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int next;
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}Edge[500010*2];
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int pre[100010];
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void add(int u,int v,int index)
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{
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Edge[index].v=v;
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Edge[index].next=pre[u];
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pre[u]=index;
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}
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int flag[100010];
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int c[100010];
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int bfs(int v)
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{
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queue <int> q;
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flag[v]=1;
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q.push(v);
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while(!q.empty())
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{
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int b=q.front();
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q.pop();
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for(int i=pre[b];i!=-1;i=Edge[i].next)
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{
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int e=Edge[i].v;
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if(flag[e]==flag[b])
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return 0;
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if(!flag[e])
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{
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flag[e]=flag[b]==1?2:1;
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q.push(e);
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}
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}
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}
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return 1;
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}
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int main()
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{
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int n,m,q,cnt=1;
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int t;
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scanf("%d",&t);
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while(t--)
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{
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scanf("%d%d%d",&n,&m,&q);
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int a,b,index=1;
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memset(flag,0,sizeof(flag));
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memset(pre,-1,sizeof(pre));
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memset(c,0,sizeof(c));
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for(int i=0;i<m;i++)
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{
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scanf("%d%d",&a,&b);
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add(a,b,index++);
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add(b,a,index++);
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c[a]++,c[b]++;
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}
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int state=0;
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for(int i=1;i<=n;i++)
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{
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if(!flag[i]&&c[i])
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{
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if(!bfs(i))
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{
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state=1;
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break;
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}
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}
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}
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printf("Case %d: ",cnt++);
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if(state)
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printf("YES\n");
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else
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printf("NO\n");
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}
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return 0;
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}
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