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 参考白皮书

#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;}