LUOGU P1505 [国家集训队]旅游 (树链剖分+线段树)

传送门

解题思路

快被调死的码农题，，，其实就是一个边权下放到点权的线段树+树剖。

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cstdlib>

using namespace std;
const int MAXN = ;
const int inf = 0x3f3f3f3f;

inline int rd(){
    int x=,f=;char ch=getchar();
    while(!isdigit(ch)) {f=ch=='-'?:;ch=getchar();}
    while(isdigit(ch))  {x=(x<<)+(x<<)+ch-'';ch=getchar();}
    return f?x:-x;
}

int n,m,head[MAXN],cnt=,to[MAXN<<],nxt[MAXN<<],val[MAXN<<],num;
int w[MAXN],wt[MAXN],id[MAXN],top[MAXN],siz[MAXN],son[MAXN],fa[MAXN],dep[MAXN];
int Sum[MAXN<<],Min[MAXN<<],Max[MAXN<<];
bool rev[MAXN<<],lazy[MAXN<<];

inline void add(int bg,int ed,int ww){
    to[++cnt]=ed,nxt[cnt]=head[bg],head[bg]=cnt,val[cnt]=ww;
}

void dfs1(int x,int f,int d){
    dep[x]=d,fa[x]=f,siz[x]=;int maxson=-,u;
    for(register int i=head[x];i;i=nxt[i]){
        u=to[i];if(u==f) continue;
        dfs1(u,x,d+);siz[x]+=siz[u];w[u]=val[i];
        if(siz[u]>maxson) {maxson=siz[u];son[x]=u;}
    }
}

void dfs2(int x,int topf){
    top[x]=topf;id[x]=++num;wt[num]=w[x];
    if(!son[x]) return;dfs2(son[x],topf);int u;
    for(register int i=head[x];i;i=nxt[i]){
        u=to[i];if(u==fa[x] || u==son[x]) continue;
        dfs2(u,u);
    }
}

inline void pushdown(int x){
    rev[x<<]^=;rev[x<<|]^=;rev[x]^=;
    Sum[x<<]=-Sum[x<<];Sum[x<<|]=-Sum[x<<|];
    swap(Min[x<<],Max[x<<]);swap(Min[x<<|],Max[x<<|]);
    Min[x<<]=-Min[x<<];Min[x<<|]=-Min[x<<|];
    Max[x<<]=-Max[x<<];Max[x<<|]=-Max[x<<|];
}

void build(int x,int l,int r){
    if(l==r) {if(l==) Min[x]=inf,Max[x]=-inf; else Sum[x]=Min[x]=Max[x]=wt[l];return;}
    int mid=(l+r)>>;
    build(x<<,l,mid);build(x<<|,mid+,r);
    Sum[x]=Sum[x<<]+Sum[x<<|];
    Min[x]=min(Min[x<<],Min[x<<|]);
    Max[x]=max(Max[x<<],Max[x<<|]);
}

void update(int x,int l,int r,int L,int R,int ww){
    if(L<=l && r<=R) {
        if(ww==-inf) {rev[x]^=;Sum[x]=-Sum[x];swap(Min[x],Max[x]);Min[x]=-Min[x];Max[x]=-Max[x];}
        else Sum[x]=Min[x]=Max[x]=ww;
        return;
    }
    int mid=(l+r)>>;if(rev[x]) pushdown(x);
    if(L<=mid) update(x<<,l,mid,L,R,ww);
    if(mid<R)  update(x<<|,mid+,r,L,R,ww);
    Sum[x]=Sum[x<<]+Sum[x<<|];
    Min[x]=min(Min[x<<],Min[x<<|]);
    Max[x]=max(Max[x<<],Max[x<<|]);
}

int query_Sum(int x,int l,int r,int L,int R){
    if(L<=l && r<=R) return Sum[x];
    int mid=(l+r)>>,ret=;if(rev[x]) pushdown(x);
    if(L<=mid) ret+=query_Sum(x<<,l,mid,L,R);
    if(mid<R)  ret+=query_Sum(x<<|,mid+,r,L,R);
    return ret;
}

int query_Max(int x,int l,int r,int L,int R){
    if(L<=l && r<=R) return Max[x];
    int mid=(l+r)>>,ret=-inf;if(rev[x]) pushdown(x);
    if(L<=mid) ret=max(ret,query_Max(x<<,l,mid,L,R));
    if(mid<R)  ret=max(ret,query_Max(x<<|,mid+,r,L,R));
    return ret;
}

int query_Min(int x,int l,int r,int L,int R){
    if(L<=l && r<=R) return Min[x];
    int mid=(l+r)>>,ret=inf;if(rev[x]) pushdown(x);
    if(L<=mid) ret=min(ret,query_Min(x<<,l,mid,L,R));
    if(mid<R)  ret=min(ret,query_Min(x<<|,mid+,r,L,R));
    return ret;
}

void updRev(int x,int y){
    while(top[x]!=top[y]){
        if(dep[top[x]]<dep[top[y]]) swap(x,y);
        update(,,n,id[top[x]],id[x],-inf);
        x=fa[top[x]];
    }
    if(dep[x]>dep[y]) swap(x,y);
    if(x!=y) update(,,n,id[x]+,id[y],-inf);
}

inline int qSum(int x,int y){
    int ret=;
    while(top[x]!=top[y]){
        if(dep[top[x]]<dep[top[y]]) swap(x,y);
        ret+=query_Sum(,,n,id[top[x]],id[x]);
        x=fa[top[x]];
    }
    if(dep[x]>dep[y]) swap(x,y);
    if(x!=y) ret+=query_Sum(,,n,id[x]+,id[y]);
    return ret;
}

inline int qMax(int x,int y){
    int ret=-inf;
    while(top[x]!=top[y]){
        if(dep[top[x]]<dep[top[y]]) swap(x,y);
        ret=max(ret,query_Max(,,n,id[top[x]],id[x]));
        x=fa[top[x]];
    }
    if(dep[x]>dep[y]) swap(x,y);
    if(x!=y) ret=max(ret,query_Max(,,n,id[x]+,id[y]));
    return ret;
}

inline int qMin(int x,int y){
    int ret=inf;
    while(top[x]!=top[y]){
        if(dep[top[x]]<dep[top[y]]) swap(x,y);
        ret=min(ret,query_Min(,,n,id[top[x]],id[x]));
        x=fa[top[x]];
    }
    if(dep[x]>dep[y]) swap(x,y);if(x!=y) ret=min(ret,query_Min(,,n,id[x]+,id[y]));
    return ret;
}

inline int pre(int x){
    return dep[to[x<<]]>dep[to[x<<^]]?to[x<<]:to[x<<^];
}

int main(){
//    freopen("wrong.out","w",stdout);
    n=rd();int x,y,z;char s[];
    for(int i=;i<n;i++){
        x=rd()+,y=rd()+,z=rd();
        add(x,y,z),add(y,x,z);
    }
    dfs1(,,);dfs2(,);build(,,n);m=rd();
    while(m--){
        scanf("%s",s+);x=rd(),y=rd();
        if(s[]=='C') update(,,n,id[pre(x)],id[pre(x)],y);
        else if(s[]=='N') updRev(x+,y+);
        else if(s[]=='S') printf("%d\n",qSum(x+,y+));
        else if(s[]=='A') printf("%d\n",qMax(x+,y+));
        else printf("%d\n",qMin(x+,y+));
    }
    return ;
}