POJ 1182

来源：互联网发布：数据科学导论编辑：程序博客网时间：2024/05/16 09:54

请参考《挑战程序设计竞赛第二版》P87~90 （并查集一章节）

刚开始一直runtime error……一直查不出来……最后发现MAXN定义成50005太小了，要3*50005才行……真是蠢……

#include<cstdio>#define MAXN 3*50000+5int par[MAXN],rank[MAXN];void init(int n){for(int i=1;i<=n;i++) par[i]=i,rank[i]=0;}int find(int x){if(par[x] == x) return x;else return( par[x] = find(par[x]) );}void unite(int x,int y){x=find(x),y=find(y);if(x == y) return;if(rank[x] < rank[y]) par[x]=y;else{par[y]=x;if(rank[x] == rank[y]) rank[x]++;}}bool isSame(int x,int y){return( find(x) == find(y) );}int main(){int n,k,d,x,y;scanf("%d%d",&n,&k);init(3*n);int ans=0;for(int i=1;i<=k;i++){scanf("%d%d%d",&d,&x,&y);if(x <=0 || x > n ||y <= 0 || y > n)//编号有问题{ans++;continue;}if(d == 1)//xy同类{if(isSame(x,y+n) || isSame(x,y+2*n)) ans++;else{unite(x,y);unite(x+n,y+n);unite(x+2*n,y+2*n); }}else if(d == 2)//x吃y{if(isSame(x,y) || isSame(x,y+2*n)) ans++;else{unite(x,y+n);unite(x+n,y+2*n);unite(x+2*n,y);}} }printf("%d\n",ans);return 0;}

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