HDU3966-Aragorn's Story-树链剖分-点权

很模板的树链剖分题

注意什么时候用线段树上的标号，什么时候用点的标号。

#pragma comment(linker, "/STACK:102400000,102400000")
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <vector>

using namespace std;
const int maxn = 50005;
int val_pre[maxn],val[maxn],siz[maxn],son[maxn],id[maxn],fa[maxn],top[maxn],dep[maxn];
int topw;
int M,N,P;

vector<int> G[maxn];

void dfs_1(int u,int f,int d)
{
    siz[u] = 1;
    fa[u]  = f;
    dep[u] = d;
    son[u] = 0;
    for(int i=0;i<G[u].size();i++)
    {
        int v = G[u][i];
        if(v == f) continue;
        dfs_1(v,u,d+1);
        siz[u] += siz[v];
        if(siz[son[u]] < siz[v])
            son[u] = v;
    }
}

void dfs_2(int u,int tp)
{
    top[u] = tp;
    id[u] = ++topw;
    if(son[u]) dfs_2(son[u],tp);
    for(int i=0;i<G[u].size();i++)
    {
        int v = G[u][i];
        if(v == fa[u]|| v==son[u]) continue;
        dfs_2(v,v);
    }
}

void debug()
{
    for(int i=1;i<=N;i++)
    {
        printf("%d siz:%d son:%d dep:%d fa:%d ",i,siz[i],son[i],dep[i],fa[i]);
        printf("top:%d id:%d
",top[i],id[i]);
    }
}

////////////////////////////////////////
//Segment Tree

#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
int add[maxn<<2];
void push_down(int rt)
{
    if(add[rt])
    {
        add[rt<<1] += add[rt];
        add[rt<<1|1] += add[rt];
        add[rt] = 0;
    }
}

void build(int l,int r,int rt)
{
    add[rt] = 0;
    if(l == r)
    {
        add[rt] = val[r];
        return ;
    }
    int m = (l+r)>>1;
    build(lson);
    build(rson);
}

void update(int L,int R,int c,int l,int r,int rt)
{
    if(L<=l && R>= r)
    {
        add[rt] += c;
        return ;
    }
    push_down(rt);
    int m = (l+r)>>1;
    if(L<=m) update(L,R,c,lson);
    if(R> m) update(L,R,c,rson);
}

int query(int x,int l,int r,int rt)
{
    if(l == r)
    {
        return add[rt];
    }
    push_down(rt);
    int m = (l+r)>>1;
    if(x <= m) query(x,lson);
    else       query(x,rson);
}

void change(int u,int v,int add)
{
    int fu = top[u],fv = top[v];
    while(fu != fv)
    {
        //printf("fu:%d u:%d v:%d fv:%d 
",fu,u,v,fv);
        if(dep[fu] < dep[fv])
        {
            swap(u,v);swap(fu,fv);
        }
        update(id[fu],id[u],add,1,topw,1);
        u = fa[fu];
        fu = top[u];
    }
    if(u == v)
    {
        update(id[u],id[v],add,1,topw,1);
        return;
    }
    else{
        if(dep[u] > dep[v]) swap(u,v);
        update(id[u],id[v],add,1,topw,1);
        return ;
    }
}

int main()
{
    //freopen("input.in","r",stdin);
    while(~scanf("%d%d%d",&N,&M,&P))
    {
        for(int i=1;i<=N;i++) scanf("%d",&val_pre[i]);
        for(int i=1,a,b;i<=M;i++)
        {
            scanf("%d%d",&a,&b);
            G[a].push_back(b);
            G[b].push_back(a);
        }
        topw = 0;
        dfs_1(1,0,1);
        dfs_2(1,1);
        for(int i=1;i<=N;i++)
        {
            val[id[i]] = val_pre[i];
        }
        build(1,topw,1);
        //debug();

        char op[10];
        int a,b,c;

        for(int i=0;i<P;i++)
        {
            scanf("%s",op);
            if(op[0] == 'I')
            {
                scanf("%d%d%d",&a,&b,&c);
                change(a,b,c);
            }
            else if(op[0] == 'D')
            {
                scanf("%d%d%d",&a,&b,&c);
                change(a,b,-c);
            }
            else if(op[0] == 'Q')
            {
                scanf("%d",&a);
                int ans = query(id[a],1,topw,1);
                printf("%d
",ans);
            }
        }
        for(int i=0;i<maxn;i++) G[i].clear();
    }
}