旅游（国家集训队）

题面

树链剖分，边权存到点上，注意边界处理

#include<iostream>
#include<cstdio>
#include<cstring>
#define maxn 100005
using namespace std;
int n,m;
struct edge
{
    int to,ne,w;  
}b[maxn];
int k=0,head[maxn];
struct tree
{
    int l,r,mx,mi,sum; 
}t[maxn*4];
struct edge2
{
     int s,t,w; 
}a[maxn];
int c[maxn];
bool rev[maxn];
int max(int x,int y)
{
    return x >y ? x: y;
}
void swap(int &x,int &y)
{
    int z=x;x=y;y=z; 
}
inline int read()
{
     int x=0;char ch=getchar();
     while(ch<'0'||ch>'9') ch=getchar();
     while(ch>='0'&&ch<='9'){ x=x*10+ch-'0'; ch=getchar(); }
     return x;  
}
void add(int u,int v,int w)
{
    k++;
    b[k].to=v;b[k].ne=head[u];b[k].w=w;head[u]=k;
}
int fa[maxn],sz[maxn],son[maxn],d[maxn],top[maxn],id[maxn],pos[maxn];
void dfs1(int x)
{
    sz[x]=1; 
    for(int i=head[x];i!=-1;i=b[i].ne)
    if(b[i].to!=fa[x]){
       fa[b[i].to]=x; d[b[i].to]=d[x]+1;
       c[b[i].to]=b[i].w;
       dfs1(b[i].to);
       sz[x]+=sz[b[i].to];
       if(son[x]==-1) son[x]=b[i].to;
       else if(sz[b[i].to]>sz[son[x]]) son[x]=b[i].to;
    }
}
int cnt=0;
void dfs2(int x,int tp)
{
     id[x]=++cnt;  pos[cnt]=x;
     top[x]=tp;
     if(son[x]!=-1) dfs2(son[x],tp);
     for(int i=head[x];i!=-1;i=b[i].ne)
     if(b[i].to!=fa[x]&&b[i].to!=son[x])  dfs2(b[i].to,b[i].to);
}
struct  Tree
{
        void swp(int &x,int &y)
        {
             int z=x; x=-y; y=-z;
        }
        void update(int z)
        {
            t[z].mx=max(t[z<<1].mx,t[z<<1|1].mx);
            t[z].mi=min(t[z<<1].mi,t[z<<1|1].mi);
            t[z].sum=t[z<<1].sum+t[z<<1|1].sum; 
        }
        void build(int l,int r,int z)
        {
            t[z].l=l;t[z].r=r;
            if(l==r){
               t[z].mx=t[z].mi=t[z].sum=c[pos[l]];
               return ;
            }
            int mid=(l+r)>>1;
            build(l,mid,z<<1);
            build(mid+1,r,z<<1|1);
            update(z);
        }
        void xg(int x,int y,int z)
        {
            if(t[z].l==t[z].r){
               t[z].mx=t[z].mi=t[z].sum=y;
               return ;
            }
            int mid=(t[z].l+t[z].r)>>1;
            if(x<=mid) xg(x,y,z<<1);
            else xg(x,y,z<<1|1);
            update(z);
        }
        void Rev(int x,int y,int z)
        {
             if(t[z].l==t[z].r){
                t[z].mx*=-1;t[z].mi*=-1;t[z].sum*=-1;
                return ;
             }
             int mid=(t[z].l+t[z].r)>>1;
             if(x<=mid) Rev(x,y,z<<1);
             if(y>mid) Rev(x,y,z<<1|1);
             update(z);
        }
        int getsum(int x,int y,int z)
        {
             if(x<=t[z].l&&t[z].r<=y) return t[z].sum;
             int ans=0;
             int mid=(t[z].l+t[z].r)>>1;
             if(x<=mid) ans+=getsum(x,y,z<<1);
             if(y>mid) ans+=getsum(x,y,z<<1|1);
             return ans;
        }
        int getmax(int x,int y,int z)
        {
             if(x<=t[z].l&&t[z].r<=y) return t[z].mx;
             int ans=-0x7fffffff;
             int mid=(t[z].l+t[z].r)>>1;
             if(x<=mid) ans=max(ans,getmax(x,y,z<<1));
             if(y>mid) ans=max(ans,getmax(x,y,z<<1|1));
             return ans;
        }   
        int getmin(int x,int y,int z)
        {
             if(x<=t[z].l&&t[z].r<=y) return t[z].mi;
             int ans=0x7fffffff;
             int mid=(t[z].l+t[z].r)>>1;
             if(x<=mid) ans=min(ans,getmin(x,y,z<<1));
             if(y>mid) ans=min(ans,getmin(x,y,z<<1|1));
             return ans;
        }   
}tr;
void revc(int x,int y)
{
     int fx=top[x],fy=top[y];
     while(fx!=fy){
        if(d[fx]<d[fy])  { swap(fx,fy); swap(x,y); }
        tr.Rev(id[fx],id[x],1);
        x=fa[fx]; fx=top[x];
     }
     if(d[x]>d[y]) swap(x,y);
     tr.Rev(id[x]+1,id[y],1);
}
int getsum(int x,int y)
{
     int fx=top[x],fy=top[y];
     int ans=0;
     while(fx!=fy){
         if(d[fx]<d[fy]) { swap(fx,fy); swap(x,y); }
         ans+=tr.getsum(id[fx],id[x],1);
         x=fa[fx]; fx=top[x];
     }
     if(d[x]>d[y]) swap(x,y);
     ans+=tr.getsum(id[x]+1,id[y],1);
     return ans;
}
int getmax(int x,int y)
{
     int fx=top[x],fy=top[y];
     int ans=-0x7fffffff;
     while(fx!=fy){
         if(d[fx]<d[fy]) { swap(fx,fy); swap(x,y); }
         ans=max(ans,tr.getmax(id[fx],id[x],1));
         x=fa[fx]; fx=top[x];
     }
     if(d[x]>d[y]) swap(x,y);
     ans=max(ans,tr.getmax(id[x]+1,id[y],1));
     return ans;
}
int getmin(int x,int y)
{
     int fx=top[x],fy=top[y];
     int ans=0x7fffffff;
     while(fx!=fy){
         if(d[fx]<d[fy]) { swap(fx,fy); swap(x,y); }
         ans=min(ans,tr.getmin(id[fx],id[x],1));
         x=fa[fx]; fx=top[x];
     }
     if(d[x]>d[y]) swap(x,y);
     ans=min(ans,tr.getmin(id[x]+1,id[y],1));
     return ans;
}
int main()
{
    //freopen("in.txt","r",stdin);
    freopen("nt2011_travel.in","r",stdin);
    freopen("nt2011_travel.out","w",stdout);
    memset(head,-1,sizeof(head));
    memset(son,-1,sizeof(son));
    memset(fa,-1,sizeof(fa));
    scanf("%d",&n);
    int x,y,z;
    char type[5];
    for(int i=1;i<n;i++){
       scanf("%d%d%d",&x,&y,&z);
       add(x,y,z);  add(y,x,z);
       a[i].s=x;a[i].t=y;
    }
    dfs1(0);
    dfs2(0,0);
    tr.build(1,n+1,1);
    scanf("%d",&m);
    while(m--){
        scanf("%s",type); scanf("%d%d",&x,&y);
        if(type[0]=='C'){
           if(fa[a[x].s]==a[x].t) tr.xg(id[a[x].s],y,1);
           else  tr.xg(id[a[x].t],y,1);
        }
        if(type[0]=='N')  revc(x,y); 
        if(type[0]=='S')  printf("%d\n",getsum(x,y)); 
        if(type[0]=='M'&&type[1]=='A') printf("%d\n",getmax(x,y));
        if(type[0]=='M'&&type[1]=='I') printf("%d\n",getmin(x,y));
    }
    return 0;
}