HDU 3966 树链剖分学习

来源：互联网发布：ubuntu uefi启动盘编辑：程序博客网时间：2024/05/17 20:25

这道题不难，看出是树链剖分就很简单，其实奇异也很明显就是一个树链剖分，不过这次不是把树链扔到线段树上，是把节点扔到线段树上。这个时候注意一下w[1] = 1就行了，其他就是线段树的一个区间覆盖的问题了。

#include <iostream>#include <cstdio>#include <cstring>#include <cmath>#include <algorithm>#include <map>#define LL long long#define FOR(i,x,y)  for(int i = x;i < y;i ++)#define IFOR(i,x,y) for(int i = x;i > y;i --)#define lrt rt<<1#define rrt rt<<1|1#define lson rt<<1,l,mid#define rson rt<<1|1,mid+1,r#define MAXN 55000using namespace std;int n,m,p;struct Edge{    int u,v;    int nt;}edge[MAXN<<1];int edge_cnt,head[MAXN];void add_edge(int u,int v){    edge[edge_cnt].u = u;    edge[edge_cnt].v = v;    edge[edge_cnt].nt = head[u];    head[u] = edge_cnt++;}int fa[MAXN],top[MAXN],sz[MAXN],son[MAXN],dep[MAXN],w[MAXN],val[MAXN],totw;void dfs1(int u,int father,int depth){    fa[u] = father; sz[u] = 1; dep[u] = depth;    int idd = -1,maxx = -1;    for(int i = head[u];i != -1;i = edge[i].nt){        int v = edge[i].v;        if(v == father) continue;        dfs1(v,u,depth+1);        sz[u] += sz[v];        if(sz[v] > maxx){            maxx = sz[v];            idd = v;        }    }    son[u] = idd;}void dfs2(int u,int father){    if(son[u] == -1)    return;    top[son[u]] = top[u];    w[son[u]] = ++totw;    dfs2(son[u],u);    for(int i = head[u];i != -1;i = edge[i].nt){        int v = edge[i].v;        if(v == father) continue;        if(v == son[u]) continue;        top[v] = v;        w[v] = ++totw;        dfs2(v,u);    }}struct Tree{    int l,r;    int lazy;}tree[MAXN<<2];void PushDown(int rt){    if(tree[rt].lazy){        tree[lrt].lazy += tree[rt].lazy;        tree[rrt].lazy += tree[rt].lazy;        tree[rt].lazy = 0;    }}void Build(int rt,int l,int r){    tree[rt].l = l; tree[rt].r = r; tree[rt].lazy = 0;    if(l == r)  return;    int mid = (l+r)>>1;    Build(lson);    Build(rson);}void Modify(int rt,int l,int r,int value){    if(tree[rt].l == l && tree[rt].r == r){        tree[rt].lazy += value;        return;    }    PushDown(rt);    int mid = (tree[rt].l + tree[rt].r)>>1;    if(r <= mid) Modify(lrt,l,r,value);    else if(l > mid) Modify(rrt,l,r,value);    else{        Modify(lson,value);        Modify(rson,value);    }}int Query(int rt,int x){    if(tree[rt].l == tree[rt].r){        return tree[rt].lazy;    }    PushDown(rt);    int mid = (tree[rt].l + tree[rt].r)>>1;    if(x <= mid)    return Query(lrt,x);    else return Query(rrt,x);}void C_Modify(int l,int r,int value){    while(top[l] != top[r]){        if(dep[top[l]] >= dep[top[r]]){            Modify(1,w[top[l]],w[l],value);            l = fa[top[l]];        }        else{            Modify(1,w[top[r]],w[r],value);            r = fa[top[r]];        }    }    if(l == r){        Modify(1,w[l],w[r],value);    }    else if(dep[l] >= dep[r]){        Modify(1,w[r],w[l],value);    }    else Modify(1,w[l],w[r],value);}int main(){    //freopen("test.in","r",stdin);    while(~scanf("%d%d%d",&n,&m,&p)){        FOR(i,1,n+1)    scanf("%d",&val[i]);        edge_cnt = 0;        memset(head,-1,sizeof(head));        FOR(i,0,m){            int u,v;            scanf("%d%d",&u,&v);            add_edge(u,v);            add_edge(v,u);        }        dfs1(1,-1,1);        totw = 0;        top[1] = 1;        w[1] = ++totw;        dfs2(1,-1);        Build(1,1,totw);        FOR(i,0,p){            char op[10];            scanf("%s",op);            if(op[0] == 'I'){                int l,r,value;                scanf("%d%d%d",&l,&r,&value);                C_Modify(l,r,value);            }            else if(op[0] == 'D'){                int l,r,value;                scanf("%d%d%d",&l,&r,&value);                C_Modify(l,r,-value);            }            else{                int x;                scanf("%d",&x);                printf("%d\n",val[x]+Query(1,w[x]));            }        }    }    return 0;}

0 0