【模板】主席树

【模板】主席树

指针版（附加内存池，未封装）

//内存池的定义（注释或删掉即可关闭内存池）
#define memory_pool 1000000

//节点的类
class node {
public:
    node* son[2];
    int v;
    node() {
        son[0]=son[1]=NULL;
    }
    void push_up() {
        v=(son[0]?son[0]->v:0)+(son[1]?son[1]->v:0);
    }
    
    #ifdef memory_pool
    void* operator new(size_t sz);
    #endif
};

#ifdef memory_pool
size_t size_node = sizeof(node);
node mem_pool[memory_pool];
node* mem_pos = mem_pool;
void* node::operator new(size_t sz) {
    node* p=mem_pos;
    mem_pos+=sz/size_node;
    return p;
}
/*
//防溢出版
bool end = 0;
void* node::operator new(size_t sz) {
    node* p;
    if(end) return p = new node[sz/size_node];
    if(mem_pos+sz/size_node > &mem_pool[memory_pool-1])return end = 1, p = new node[sz/size_node];
    p = mem_pos;
    mem_pos += sz/size_node;
    return p;
}
*/
#endif

//建立一棵具有所有节点的空树
void build(node* &p, int l, int r) {
    if(! p)p = new node;
    if(l == r)return;
    int mid = (l + r) >> 1;
    build(p->son[0], l, mid);
    build(p->son[1], mid + 1, r);
}
//建立一棵有部分节点的空树
void build(node* &p, int l, int r, int x, int c) {
    if(! p)p = new node;
    if(l == r)return void(p->v = c);
    int mid = (l + r) >> 1;
    if(x <= mid)build(p->son[0], l, mid, x, c);
    else build(p->son[1], mid + 1, r, x, c);
    p->push_up();
}
//新建一个版本（单点修改）
void update(node* &p, node* rt, int l, int r, int x, int c) {
    if(! rt)return build(p, l, r, x, c);
    if(! p)p = new node;
    if(l == r)return void(p->v = rt->v + c);
    int mid = (l + r) >> 1;
    if(x <= mid)p->son[1] = rt->son[1], update(p->son[0], rt->son[0], l, mid, x, c);
    else p->son[0] = rt->son[0], update(p->son[1], rt->son[1], mid+1, r, x, c);
    p->push_up();
}
//区间查询
int query(node* &p,int l,int r,int x,int y) {
    if(!p)return 0;
    if(l>=x&&r<=y)return p->v;
    int mid=(l+r)>>1;
    int ans=0;
    if(x<=mid)ans+=query(p->son[0],l,mid,x,y);
    if(y>mid)ans+=query(p->son[1],mid+1,r,x,y);
    return ans;
}

转载于:https://www.cnblogs.com/akakw1/p/9873446.html