bzoj 1924: [Sdoi2010]所驼门王的宝藏

bzoj1924

tarjan后dp
常规操作求最长路

#include<cstdio>
#include<iostream>
#include<algorithm>
#include<map>
#define LL long long
const int maxn = 5000007;
inline int read()
{
    int x=0,f=1; 
	char c=getchar();
    while(c<'0' || c>'9') {if (c=='-') f=-1; c=getchar();}
    while(c>='0' && c<='9') {x=x*10+c-'0'; c=getchar();}
    return x*f;
}
struct data{
    int x,y,id,opt;
}a[maxn];
struct edge{
    int to,next;
}edge[maxn<<2],E[maxn];
int head[maxn],H[maxn>>1],cnt,recnt,ind,top,n,x,y;
bool inq[maxn],vis[maxn>>1];
int ans; 
int q[maxn],dfn[maxn],low[maxn];
int size[maxn>>1],belong[maxn],tot;
bool cmp_x(data a,data b) {
    return a.x<b.x;
}
bool cmp_y(data a,data b) {
    return a.y<b.y;
}
void add_edge(int x, int y) {
    edge[++cnt].to=y; edge[cnt].next=head[x]; head[x]=cnt;
}
void Add_edge(int x, int y) {
    E[++recnt].to=y; E[recnt].next=H[x]; H[x]=recnt;
}
void tarjan(int x) {
    q[++top]=x; dfn[x]=low[x]=++ind;
    inq[x]=1;
    for(int i=head[x];i;i=edge[i].next)
        if(!dfn[edge[i].to]) {
            tarjan(edge[i].to);
            low[x]=std::min(low[x],low[edge[i].to]);
        }
        else if (inq[edge[i].to]) low[x]=std::min(low[x],dfn[edge[i].to]);
    int now=-1;
    if(dfn[x]==low[x]) {
        tot++;
        while(now!=x) {
            now=q[top--];
            belong[now]=tot;
            size[tot]++;
            inq[now]=0;
        }
    }
}
void dfs(int x) {
    vis[x]=1;int mx=0;
    for(int i=H[x];i;i=E[i].next){
        if(!vis[E[i].to]) 
			dfs(E[i].to);
        mx=std::max(size[E[i].to],mx);
    }
    ans=std::max(ans,size[x]+=mx);
}
std::map<LL,int>GG;
int main() {
    n=read();x=read();y=read();
    for (int i=1; i<=n; i++) a[i].x=read(),
		a[i].y=read(),a[i].opt=read(),GG[(LL)a[i].x*maxn+a[i].y]=i,a[i].id=i;
	std::sort(a+1,a+n+1,cmp_x);
    for(int i=1;i<=n;i++)
        if(a[i].opt==1) {
            for (int j=i-1;j>=1; j--)
                if (a[i].x==a[j].x) add_edge(a[i].id,a[j].id);
                    else break;
            for (int j=i+1; j<=n; j++)
                if (a[i].x==a[j].x) add_edge(a[i].id,a[j].id);
                    else break;
		}
	std::sort(a+1,a+n+1,cmp_y);
    for(int i=1;i<=n;i++)
        if(a[i].opt==2)
        {
            for(int j=i-1;j>=1;j--)
                if(a[i].y==a[j].y) 
					add_edge(a[i].id,a[j].id);
                else break;
            for(int j=i+1;j<=n;j++)
                if(a[i].y==a[j].y) 
					add_edge(a[i].id,a[j].id);
                    else break;
        }
    for(int i=1;i<=n;i++)
        if(a[i].opt==3){
            for(int j=a[i].x-1; j<=a[i].x+1; j++)
                for(int k=a[i].y-1; k<=a[i].y+1; k++)
                    if(j!=a[i].x||k!=a[i].y)
                        if(GG[(LL)j*maxn+k]) 
							add_edge(a[i].id,GG[(LL)j*maxn+k]);
        }
    for(int i=1; i<=n; i++)
        if(!dfn[i])tarjan(i);
    for(int x=1;x<=n;x++)
        for(int i=head[x];i;i=edge[i].next)
            if(belong[x]!=belong[edge[i].to])    
                Add_edge(belong[x],belong[edge[i].to]);
    for(int i=1;i<=tot;i++)
        if(!vis[i]) dfs(i);
    printf("%d
",ans);
    return 0;
}