【做题记录】2025刷题计划--线段树

A. 「SDOI2014」旅行
给每个宗教开一棵线段树，树剖 \(+\) 线段树单点修改区间查询即可。

Code

#include<bits/stdc++.h>
#define ll long long
#define il inline
#define read(x){\char ch;\int fu=1;\while(!isdigit(ch=getchar()))\fu-=(ch=='-')<<1;\x=ch&15;\while(isdigit(ch=getchar()))\x=(x<<1)+(x<<3)+(ch&15);\x*=fu;\
}
#define int ll
#define pb push_back
using namespace std;
namespace asbt{
namespace cplx{bool begin;}
const int maxn=1e5+5,maxm=5e6+5;
int n,m,a[maxn],b[maxn],cnt;
int top[maxn],fa[maxn],dfn[maxn];
int sz[maxn],hes[maxn],dep[maxn];
vector<int> e[maxn];
il void dfs1(int u){dep[u]=dep[fa[u]]+1;sz[u]=1;int mxs=0;for(int v:e[u]){if(v==fa[u]){continue;}fa[v]=u;dfs1(v);sz[u]+=sz[v];if(mxs<sz[v]){mxs=sz[v];hes[u]=v;}}
}
il void dfs2(int u){dfn[u]=++cnt;if(!top[u]){top[u]=u;}if(hes[u]){top[hes[u]]=top[u];dfs2(hes[u]);}for(int v:e[u]){if(v==fa[u]||v==hes[u]){continue;}dfs2(v);}
}
int rt[maxn],ls[maxm],rs[maxm];
int tot,sum[maxm],mx[maxm];
il void pushup(int id){sum[id]=sum[ls[id]]+sum[rs[id]];mx[id]=max(mx[ls[id]],mx[rs[id]]);
}
il void upd(int &id,int l,int r,int pos,int val){if(!id){id=++tot;}if(l==r){sum[id]=mx[id]=val;return ;}int mid=(l+r)>>1;if(pos<=mid){upd(ls[id],l,mid,pos,val);}else{upd(rs[id],mid+1,r,pos,val);}pushup(id);
}
il int qsum(int id,int L,int R,int l,int r){if(!id){return 0;}if(L>=l&&R<=r){return sum[id];}int mid=(L+R)>>1,res=0;if(l<=mid){res+=qsum(ls[id],L,mid,l,r);}if(r>mid){res+=qsum(rs[id],mid+1,R,l,r);}return res;
}
il int qmx(int id,int L,int R,int l,int r){if(!id){return 0;}if(L>=l&&R<=r){return mx[id];}int mid=(L+R)>>1,res=0;if(l<=mid){res=max(res,qmx(ls[id],L,mid,l,r));}if(r>mid){res=max(res,qmx(rs[id],mid+1,R,l,r));}return res;
}
namespace cplx{bool end;il double usdmem(){return (&begin-&end)/10485796.0;}
}
signed main(){read(n)read(m);for(int i=1;i<=n;i++){read(a[i])read(b[i]);}for(int i=1,u,v;i<n;i++){read(u)read(v);e[u].pb(v),e[v].pb(u);}dfs1(1),dfs2(1);for(int i=1;i<=n;i++){upd(rt[b[i]],1,n,dfn[i],a[i]);}while(m--){char opt[5];int u,v;scanf(" %s",opt+1);read(u)read(v);switch(opt[2]){case 'C':{upd(rt[b[u]],1,n,dfn[u],0);b[u]=v;upd(rt[b[u]],1,n,dfn[u],a[u]);break;}case 'W':{a[u]=v;upd(rt[b[u]],1,n,dfn[u],a[u]);break;}case 'S':{int res=0,x=b[u];while(top[u]!=top[v]){
//					puts("666");if(dep[top[u]]<dep[top[v]]){swap(u,v);}res+=qsum(rt[x],1,n,dfn[top[u]],dfn[u]);u=fa[top[u]];}if(dep[u]>dep[v]){swap(u,v);}res+=qsum(rt[x],1,n,dfn[u],dfn[v]);printf("%lld\n",res);break;}default:{int res=0,x=b[u];while(top[u]!=top[v]){if(dep[top[u]]<dep[top[v]]){swap(u,v);}res=max(res,qmx(rt[x],1,n,dfn[top[u]],dfn[u]));u=fa[top[u]];}if(dep[u]>dep[v]){swap(u,v);}res=max(res,qmx(rt[x],1,n,dfn[u],dfn[v]));printf("%lld\n",res);break;}}}return 0;
}
}
signed main(){return asbt::main();}