BZOJ 1036 树的统计(树链剖分)
点权树链剖分模板题。
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
# include <cstdio> # include <cstring> # include <cstdlib> # include <iostream> # include <vector> # include <queue> # include <stack> # include <map> # include <set> # include <cmath> # include <algorithm> using namespace std; # define lowbit(x) ((x)&(-x)) # define pi acos(-1.0) # define eps 1e-9 # define MOD 1000000007 # define INF 1000000000 # define mem(a,b) memset(a,b,sizeof(a)) # define FOR(i,a,n) for(int i=a; i<=n; ++i) # define FO(i,a,n) for(int i=a; i<n; ++i) # define bug puts("H"); # define lch p<<1,l,mid # define rch p<<1|1,mid+1,r # define mp make_pair # define pb push_back typedef pair<int,int> PII; typedef vector<int> VI; # pragma comment(linker, "/STACK:1024000000,1024000000") typedef long long LL; int Scan() { int res=0, flag=0; char ch; if((ch=getchar())=='-') flag=1; else if(ch>='0'&&ch<='9') res=ch-'0'; while((ch=getchar())>='0'&&ch<='9') res=res*10+(ch-'0'); return flag?-res:res; } void Out(int a) { if(a<0) {putchar('-'); a=-a;} if(a>=10) Out(a/10); putchar(a%10+'0'); } const int N=30005; //Code begin... struct Edge{int p, next;}edge[N<<1]; int head[N], cnt, node[N], n; int seg[N<<2][2], fa[N], size[N], dep[N], p[N], top[N], son[N], pos; void add_edge(int u, int v){edge[cnt].p=v; edge[cnt].next=head[u]; head[u]=cnt++;} void init(){cnt=1; mem(son,-1); pos=1;} void dfs(int x, int pre, int d) { fa[x]=pre; dep[x]=d; size[x]=1; for (int i=head[x]; i; i=edge[i].next) { int v=edge[i].p; if (v==pre) continue; dfs(v,x,d+1); size[x]+=size[v]; if (son[x]==-1||size[v]>size[son[x]]) son[x]=v; } } void get_pos(int x, int sp) { top[x]=sp; p[x]=pos++; if (son[x]==-1) return ; get_pos(son[x],sp); for (int i=head[x]; i; i=edge[i].next) { int v=edge[i].p; if (v!=son[x]&&v!=fa[x]) get_pos(v,v); } } void push_up(int p) { seg[p][0]=max(seg[p<<1][0], seg[p<<1|1][0]); seg[p][1]=seg[p<<1][1]+seg[p<<1|1][1]; } void update(int p, int l, int r, int L, int val) { if (L>r||L<l) return ; if (L==l&&L==r) seg[p][0]=seg[p][1]=val; else { int mid=(l+r)>>1; update(lch,L,val); update(rch,L,val); push_up(p); } } int query(int p, int l, int r, int L, int R, int flag) { if (L>r||R<l) { if (flag) return 0; else return -INF; } if (L<=l&&R>=r) return seg[p][flag]; int mid=(l+r)>>1; if (flag) return query(lch,L,R,flag)+query(rch,L,R,flag); else return max(query(lch,L,R,flag),query(rch,L,R,flag)); } int Qtree(int l, int r, int flag) { int f1=top[l], f2=top[r], ans; if (flag) ans=0; else ans=-INF; bool mark=false; while (f1!=f2) { mark=true; if (dep[f1]<dep[f2]) swap(f1,f2), swap(l,r); if (flag==0) ans=max(ans,query(1,1,n,p[f1],p[l],flag)); else ans+=query(1,1,n,p[f1],p[l],flag); l=fa[f1]; f1=top[l]; } if (dep[l]>dep[r]) swap(l,r); if (flag==0) ans=max(ans,query(1,1,n,p[l],p[r],flag)); else ans+=query(1,1,n,p[l],p[r],flag); return ans; } int main () { int u, v, q, l, r; char flag[10]; init(); scanf("%d",&n); FO(i,1,n) scanf("%d%d",&u,&v), add_edge(u,v), add_edge(v,u); dfs(1,0,0); get_pos(1,1); FOR(i,1,n) scanf("%d",node+i), update(1,1,n,p[i],node[i]); scanf("%d",&q); while (q--) { scanf("%s%d%d",flag,&l,&r); if (flag[0]=='C') update(1,1,n,p[l],r); else printf("%d\n",Qtree(l,r,flag[1]=='S')); } return 0; }