洛谷2024 食物链

传送门

并查集 被ykk嘲笑了。

每个点拆成三个，分别表示我，我吃的东西，我被吃的东西。

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//Twenty #include<algorithm> #include<iostream> #include<cstdlib> #include<cstring> #include<cstdio> #include<cmath> #include<ctime> #include<queue> const int maxn=(1e5+7)*3; using namespace std; typedef long long LL; int o,x,y,u,v,n,k,fa[maxn],eat[maxn],ans;   void read(int &ret) {     int f=1; ret=0; char ch=getchar();     while(ch!='-'&&(ch<'0'||ch>'9')) ch=getchar();     if(ch=='-') f=-1,ch=getchar();     for(;ch>='0'&&ch<='9';ch=getchar()) ret=ret*10+ch-'0'; ret*=f; }   int find(int x) {     return x==fa[x]?x:fa[x]=find(fa[x]); }   void link(int x,int y) {     if(find(x)==find(y)) return;     fa[x]=y; }   void init() {     read(n); read(k);     for(int i=1;i<=3*n;i++) fa[i]=i;     for(int i=1;i<=k;i++) {         scanf("%d%d%d",&o,&x,&y);         if(x>n||y>n||(o==2&&x==y)) {             ans++;             continue;         }         if(o==1) {             if(find(x+n)==find(y)||find(x+2*n)==find(y)) {                 ans++;                 continue;             }             u=find(x),v=find(y);             if(u!=v) fa[u]=v;             u=find(x+n); v=find(y+n);             if(u!=v) fa[u]=v;             u=find(x+2*n); v=find(y+2*n);             if(u!=v) fa[u]=v;         }         else {             if(find(x)==find(y)||find(x+2*n)==find(y)) {                 ans++;                 continue;             }             u=find(x+n); v=find(y);             if(u!=v) fa[u]=v;             u=find(y+2*n); v=find(x);             if(u!=v) fa[u]=v;             u=find(x+2*n); v=find(y+n);             if(u!=v) fa[u]=v;         }     }     printf("%d\n",ans); }   int main() {     init();     return 0; }