lightoj1348（树链剖分&线段树）

常规树链剖分题，把点权哈希到数组中，用线段树维护。

#include<cstdio>#include<vector>#include<cstring>using namespace std;const int N = 30000+10;int dep[N],siz[N],fa[N],id[N],son[N],val[N],top[N],num;vector<int>v[N];void dfs1(int u, int f, int d) {    dep[u] = d;    siz[u] = 1;    son[u] = 0;    fa[u] = f;    for (int i = 0; i < v[u].size(); i++) {        int ff = v[u][i];        if (ff == f) continue;        dfs1(ff, u, d + 1);        siz[u] += siz[ff];        if (siz[son[u]] < siz[ff])            son[u] = ff;    }}void dfs2(int u, int tp) {    top[u] = tp;    id[u] = ++num;    if (son[u]) dfs2(son[u], tp);    for (int i = 0; i < v[u].size(); i++) {        int ff = v[u][i];        if (ff == fa[u] || ff == son[u]) continue;        dfs2(ff, ff);    }}int tree[N<<2];void update(int pos,int w,int l,int r,int root){    if(l==r) {tree[root] = w; return ; }    int mid = (l+r)/2; int tmp = root*2;    if(pos<=mid) update(pos,w,l,mid,tmp);    else if(pos>mid) update(pos,w,mid+1,r,tmp+1);    tree[root] = tree[tmp] + tree[tmp+1];}int query(int L,int R,int l,int r,int root){    if(L<=l&&R>=r){return tree[root]; }    int mid = (l+r)/2; int tmp = root*2;    int ans = 0;    if(mid>=L) ans += query(L,R,l,mid,tmp);    if(mid<R) ans += query(L,R,mid+1,r,tmp+1);    return ans ;}int _find(int u,int v){    int f1=top[u],f2=top[v],tmp=0;    while(f1!=f2){        if(dep[f1]<dep[f2]){            swap(f1,f2);            swap(u,v);        }        tmp+=query(id[f1],id[u],1,num,1);        u=fa[f1];f1=top[u];    }    if(dep[u]>dep[v]) swap(u,v);    tmp+=query(id[u],id[v],1,num,1);    return tmp;}int main(){    int cases,n,a,b,c,t=1;    scanf("%d",&cases);    while(cases--)    {        scanf("%d",&n);        for(int i=0;i<=n;i++) v[i].clear();        memset(tree,0,sizeof(tree));        for(int i=1;i<=n;i++) scanf("%d",&val[i]);        for(int i=1;i<n;i++)        {            scanf("%d%d",&a,&b); a++; b++;            v[a].push_back(b);            v[b].push_back(a);        }        num = 0; dfs1(1,0,1); dfs2(1,1);        for(int i=1;i<=n;i++) update(id[i],val[i],1,num,1);        int q ; scanf("%d",&q);        printf("Case %d:\n",t++);        while(q--)        {            scanf("%d%d%d",&a,&b,&c); b++;            if(a==1) update(id[b],c,1,num,1);            else c++,printf("%d\n",_find(b,c));        }    }    return 0;}