bzoj 1023: [SHOI2008]cactus仙人掌图 2125: 最短路 4728: 挪威的森林 静态仙人掌上路径长度的维护系列

#include<cstdio>
char buf[5000000],*ptr=buf-1;
int _(){
    int x=0,c=*++ptr;
    while(c<48)c=*++ptr;
    while(c>47)x=x*10+c-48,c=*++ptr;
    return x;
}
const int N=500007;
int es[N],enx[N],ev[N],e0[N],e1[N],ep=2;
int dfn[N],low[N],tk=0,ss[N],sp=0,os[N],op,q[N],ql,qr;
int n,m,D,idp,ans=0,f1[N],f2[N];
void ae(int*e,int a,int b,int c){
    es[ep]=b;enx[ep]=e[a];ev[ep]=c;e[a]=ep++;
    es[ep]=a;enx[ep]=e[b];ev[ep]=c;e[b]=ep++;
}
int min(int a,int b){return a<b?a:b;}
void maxs(int&a,int b){if(a<b)a=b;}
void maxs(int&a,int&b,int c){
    if(a<=c)b=a,a=c;
    else if(b<c)b=c;
}
void tj(int w){
    dfn[w]=low[w]=++tk;
    for(int i=e0[w];i;i=enx[i]){
        int u=es[i];
        if(!u)continue;
        es[i^1]=0;
        if(!dfn[u]){
            ss[++sp]=u;
            tj(u);
            if(ss[sp]==u)--sp,ae(e1,w,u,1);
        }else if((low[w]=min(low[w],dfn[u]))==dfn[u]){
            op=0;
            while(sp&&dfn[ss[sp]]>dfn[u])os[++op]=ss[sp--];
            ae(e1,u,++idp,0);
            for(int j=1;j<=op;++j)ae(e1,idp,os[j],min(j,op+1-j));
        }
    }
}
void dfs(int w,int pa){
    for(int i=e1[w];i;i=enx[i]){
        int u=es[i];
        if(u==pa)continue;
        dfs(u,w);
        maxs(f1[w],f2[w],f1[u]+ev[i]); 
    }
    if(w<=n)maxs(ans,f1[w]+f2[w]);
    else{
        op=0;
        for(int i=e1[w];i;i=enx[i]){
            int u=es[i];
            if(u!=pa)os[++op]=u;
        }
        os[++op]=pa;
        D=op>>1;
        ql=1,qr=0;
        for(int i=1;i<=D;++i)os[op+i]=os[i];
        op+=D;
        for(int i=1;i<=op;++i){
            while(ql<=qr&&q[ql]+D<i)++ql;
            if(ql<=qr)maxs(ans,f1[os[q[ql]]]+f1[os[i]]-q[ql]+i);
            while(ql<=qr&&f1[os[q[qr]]]-q[qr]<=f1[os[i]]-i)--qr;
            q[++qr]=i;
        }
        ql=1,qr=0;
        for(int i=op;i;--i){
            while(ql<=qr&&q[ql]-D>i)++ql;
            if(ql<=qr)maxs(ans,f1[os[q[ql]]]+f1[os[i]]+q[ql]-i);
            while(ql<=qr&&f1[os[q[qr]]]+q[qr]<=f1[os[i]]+i)--qr;
            q[++qr]=i;
        }
    }
}
int main(){
    fread(buf,1,sizeof(buf),stdin);
    idp=n=_();m=_();
    for(int i=0,c,a,b;i<m;++i){
        c=_();
        a=_();
        for(int j=1;j<c;++j){
            b=_();
            ae(e0,a,b,1);
            a=b;
        }
    }
    tj(1);
    dfs(1,0);
    printf("%d",ans);
    return 0;
}

#include<cstdio>
#include<algorithm>
char buf[1000000],*ptr=buf-1;
int _(){
    int x=0,c=*++ptr;
    while(c<48)c=*++ptr;
    while(c>47)x=x*10+c-48,c=*++ptr;
    return x;
}
const int N=100007;
int n,m,q;
int es[N],enx[N],ev[N],e0[20007],e1[20007],ep=2,ss[20007],sp=0,idp,os[20007],op,d1[20007],d2[20007];
int dfn[20007],low[20007],tk=0;
void ae(int*e,int a,int b,int c){
    es[ep]=b;enx[ep]=e[a];ev[ep]=c;e[a]=ep++;
    es[ep]=a;enx[ep]=e[b];ev[ep]=c;e[b]=ep++;
}
int min(int a,int b){return a<b?a:b;}
void f0(int w){
    dfn[w]=low[w]=++tk;
    for(int i=e0[w];i;i=enx[i]){
        int u=es[i];
        if(!u)continue;
        if(!dfn[u]){
            ss[++sp]=i;
            es[i^1]=0;
            f0(u);
            low[w]=min(low[w],low[u]);
            if(ss[sp]==i)--sp,ae(e1,w,u,ev[i]);
        }else if((low[w]=min(low[w],dfn[u]))==dfn[u]){
            ++idp;op=0;
            ae(e1,idp,u,0);
            op=0;
            int s1=ev[i],s2=0;
            while(sp&&dfn[es[ss[sp]]]>dfn[u]){
                int e=ss[sp--];
                os[op++]=e;
                s2+=ev[e];
            }
            for(int p=0;p<op;++p){
                int e=os[p];
                ae(e1,idp,es[e],min(d1[es[e]]=s1,s2));
                d2[es[e]]=s1+s2;
                s1+=ev[e],s2-=ev[e];
            }
        }
    }
}
int fa[16][20007],dep[20007],Dep[20007];
void f1(int w,int pa){
    fa[0][w]=pa;
    for(int i=e1[w];i;i=enx[i]){
        int u=es[i];
        if(u==pa)continue;
        dep[u]=dep[w]+1;
        Dep[u]=Dep[w]+ev[i];
        f1(u,w);
    }
}
int main(){
    fread(buf,1,sizeof(buf),stdin);
    n=_();m=_();q=_();
    idp=n;
    for(int i=1,a,b,c;i<=m;++i){
        a=_();b=_();c=_();
        ae(e0,a,b,c);
    }
    f0(1);
    f1(1,0);
    for(int i=1;i<16;++i)for(int j=1;j<=idp;++j)fa[i][j]=fa[i-1][fa[i-1][j]];
    for(int i=0,a,b,ans;i<q;++i){
        a=_();b=_();
        if(dep[a]<dep[b])std::swap(a,b);
        ans=Dep[a]+Dep[b];
        for(int d=0,s=dep[a]-dep[b];d<16;++d)if(s>>d&1)a=fa[d][a];
        if(a==b)ans-=Dep[a]*2;
        else{
            for(int d=15;~d;--d)if(fa[d][a]!=fa[d][b])a=fa[d][a],b=fa[d][b];
            if(fa[0][a]<=n)ans-=Dep[fa[0][a]]*2;
            else{
                ans-=Dep[a]+Dep[b];
                int s=d1[a]-d1[b];
                if(s<0)s=-s;
                ans+=min(s,d2[a]-s);
            }
        }
        printf("%d\n",ans);
    }
    return 0;
}