HDU 3726 Graph and Queries treap树

题目来源：HDU 3726 Graph and Queries

题意：见白书

思路：刚学treap 參考白皮书

#include <cstdio>
#include <cstring>
#include <cstdlib>
using namespace std;

struct Node
{
    Node *ch[2];
    int r;
    int v;
    int s;
    Node(int v): v(v) {
        ch[0] = ch[1] = NULL; r = rand(); s = 1;
    }
    bool operator < (const Node& rhs) const{
        return r < rhs.r;
    }
    int cmp(int x) const{
        if(x == v) return -1;
        return x < v ?
 0 : 1;
    }
    void maintain(){
        s = 1;
        if(ch[0] != NULL) s += ch[0]->s;
        if(ch[1] != NULL) s += ch[1]->s;
    }
};

void rotate(Node* &o, int d){
    Node* k = o->ch[d^1]; o->ch[d^1] = k->ch[d]; k->ch[d] = o;
    o->maintain(); k->maintain(); o = k;
}

void insert(Node* &o, int x){
    if(o == NULL){
        o = new Node(x);
    }
    else{
        int d = (x < o->v ? 0 : 1);
        insert(o->ch[d], x);
        if(o->ch[d] > o) rotate(o, d^1);
    }
    o->maintain();
    //printf("--------+%d\n", o->s);
}

void remove(Node* &o, int x){
    int d = o->cmp(x);
    if(d == -1){
        Node* u = o;    
        if(o->ch[0] != NULL && o->ch[1] != NULL){            
            int d2 = o->ch[0] > o->ch[1] ? 1 : 0;
            rotate(o, d2); remove(o->ch[d2], x);
        }
        else{
            if(o->ch[0] == NULL) o = o->ch[1];
            else o = o->ch[0];
            delete u;
        }
    }
    else
        remove(o->ch[d], x);
    if(o != NULL) o->maintain();
}

const int maxn = 20010;
const int maxc = 500010;
int n, m, w[maxn], from[maxn*3], to[maxn*3], removed[maxn*3];
int f[maxn];

Node* root[maxn];

struct Command
{
    char type;
    int x, p;
    Command(){}
    Command(char type, int x, int p): type(type), x(x), p(p) { }
}commands[maxc];

int find(int x)
{
    if(x != f[x])
        return f[x] = find(f[x]);
    return f[x];
}
int kth(Node* o, int k){
    if(o == NULL || k <= 0 || k > o->s)
        return 0;
    int s = (o->ch[1] == NULL ? 0 : o->ch[1]->s);
    if(k == s+1) return o->v;
    else if(k <= s) return kth(o->ch[1], k);
    else return kth(o->ch[0], k-s-1);
}

void mergeto(Node* &src, Node* &dest){
    
    if(src->ch[0] != NULL) mergeto(src->ch[0], dest);
    if(src->ch[1] != NULL) mergeto(src->ch[1], dest);
    insert(dest, src->v);
    delete src;
    src = NULL;
}

void add_edge(int x){
    int u = find(from[x]), v = find(to[x]);
    //printf("-/++++%d %d\n", u, v);
    if(u != v){
        if(root[u]->s > root[v]->s){
            f[v] = u;
            //printf("----%d %d\n", root[v]->s, root[u]->s);
            mergeto(root[v], root[u]);
            //printf("----%d\n", root[u]->s);
        }
        else{
            f[u] = v;
            //printf("----%d %d\n", root[u]->s, root[v]->s);
            mergeto(root[u], root[v]);
            //printf("++++%d\n", root[v]->s);
        }
    }
}

void removetree(Node* &x){
    if(x->ch[0] != NULL) removetree(x->ch[0]);
    if(x->ch[1] != NULL) removetree(x->ch[1]);
    delete x;
    x = NULL;
}

int query_cnt;
long long query_tol;

void query(int x, int k){
    query_cnt++;
    //printf("%d %d\n", root[find(x)]->s, kth(root[find(x)], k));
    query_tol += kth(root[find(x)], k);
}

void change_weight(int x, int v){
    int u = find(x);
    remove(root[u], w[x]);
    insert(root[u], v);
    w[x] = v;
}
int main()
{
    int kase = 0;
    while(scanf("%d %d", &n, &m) && (n||m))
    {
        for(int i = 1; i <= n; i++)
            scanf("%d", &w[i]);
        for(int i = 1; i <= m; i++)
            scanf("%d %d", &from[i], &to[i]);
        memset(removed, 0, sizeof(removed));
        int c = 0;
        while(1)
        {
            char type[2];
            int x, p = 0, v = 0;
            scanf("%s", type);
            if(type[0] == 'E')
                break;
            scanf("%d", &x);
            if(type[0] == 'D')
                removed[x] = 1;
            if(type[0] == 'Q')
                scanf("%d", &p);
            if(type[0] == 'C')
            {
                scanf("%d", &v);
                p = w[x];
                w[x] = v;
            }
            commands[c++] = Command(type[0], x, p);
        }
        
        for(int i = 1; i <= n; i++)
        {
            f[i] = i;
            if(root[i] != NULL)
                removetree(root[i]);
            root[i] = new Node(w[i]);
            //printf("******%d\n", root[i]->s);
        }
        for(int i = 1; i <= m; i++)
            if(!removed[i])
            {
                add_edge(i);
                //puts("gh");
            }
        query_tol = query_cnt = 0;
        for(int i = c-1; i >= 0; i--){
            if(commands[i].type == 'D')
                add_edge(commands[i].x);
            if(commands[i].type == 'Q')
                query(commands[i].x, commands[i].p);
            if(commands[i].type == 'C')
                change_weight(commands[i].x, commands[i].p);
        }
        printf("Case %d: %.6lf\n", ++kase, query_tol/(double)query_cnt);
    }
    return 0;
}