39 lines
673 B
C++
39 lines
673 B
C++
#include <stdio.h>
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int p[1222];
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int i;
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int find(int x)
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{
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if(x!=p[x])
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p[x]=find(p[x]);
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return p[x];
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}
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int hebing(int x,int y)
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{
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return p[x]=y;
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}
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int main()
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{
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int n,m,x,y,x1,y1;
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while(~scanf("%d%d",&n,&m)&&n)
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{
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for(i=1;i<=1222;i++)
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p[i]=i;
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for(i=1;i<=m;i++)
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{
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scanf("%d%d",&x,&y);
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x1=find(x);
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y1=find(y);
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if(x1!=y1)
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hebing(x1,y1);
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}
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int ans=0;
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for(i=1;i<=n;i++)
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{
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if(p[i]==i)
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ans++;
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}
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printf("%d\n",ans-1);
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}
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return 0;
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}
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