kosaraju求调
查看原帖
kosaraju求调
285617
黑影洞人楼主2022/3/6 07:59
#include<cstdio>
#include<algorithm>
#include<vector>
#include<cstring>
#define N 114514
using namespace std;
int head[N],dp[N],cmp[N],sz[N],to[N],nxt[N],rh[N],rt[N],rn[N],rr[N],tot,n,f[N],cnt,vis[N];
int find(int x){
	if(!x||dp[x])return dp[x];
	return dp[x]=find(rr[x])+sz[x];
}
vector<int >out;
void add(int u,int v){
	to[++tot]=v,rt[tot]=u;
	nxt[tot]=head[u],rn[tot]=rh[v];
	head[u]=tot,rh[v]=tot;
}
void dfs(int x){
	vis[x]=1;
	for(int i=head[x];i;i=nxt[i]){
		int y=to[i];
		if(!vis[y])dfs(y);
	}
	out.push_back(x);
}
void rd(int x,int ff){
	vis[x]=1;cmp[x]=ff;sz[ff]++;
	for(int i=rh[x];i;i=rn[i]){
		int y=rt[i];
		if(!vis[y])rd(y,ff);
	}
}
int kosaraju(){
	memset(vis,0,sizeof(vis));
	out.clear();
	for(int i=1;i<=n;i++)if(!vis[i])dfs(i);
	int f=0;
	memset(vis,0,sizeof(vis));
	for(int i=out.size()-1;i>=0;i--)if(!vis[out[i]])rd(out[i],++f);
	return f;
}
signed main(){
	scanf("%d",&n);
	for(int i=1;i<=n;i++){
		int k=0;
		add(i,scanf("%d",&k));
	}
	int sb=kosaraju();
	
	for(int i=1;i<=n;i++){
		if(cmp[i]!=cmp[to[i]]){
			rr[cmp[i]]=cmp[to[i]];
		}
	}
	for(int i=1;i<=n;i++){
		printf("%d\n",find(cmp[i]));
	}
	return 0;
}
2022/3/6 07:59
加载中...