一起来学习一个treap【POJ 3458】&【LA 5031】

POJ 3458

链接：

代码：

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

struct node{
node* ch[2];
int r,s,v,ans;
node(int x,int y){ch[0] = ch[1] = NULL;r = rand();s = 1;v = x;ans = y;}
int cmp(int x)
{
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,int y)
{
if(o == NULL) o = new node(x,y);
else
{
int d = (x < o->v ? 0 : 1);
insert(o->ch[d],x,y);
if(o->ch[d]->r > o->r)rotate(o,d^1);
}
o->maintain();
}

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]->r > o->ch[1]->r ? 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();
}

int kth(node* &o,int k)
{
if(o == NULL || k <= 0 || k > o->s) return 0;
int s = (o->ch[0] == NULL ? 0 : o->ch[0]->s);
if(k == s+1)
{
printf("%d\n",o->ans);
return o->v;
}
else
if(k <= s) return kth(o->ch[0],k);
else return kth(o->ch[1],k-s-1);
}

node * root;
int main()
{
int len = 0,p,x,y;
while(scanf("%d",&p) && p)
{
if(p == 1)
{
scanf("%d%d",&x,&y);
insert(root,y,x);
len++;
}
else
{
if(len == 0){printf("0\n");continue;}
if(p == 2) x = kth(root,len);
if(p == 3) x = kth(root,1);
remove(root,x);
len--;
}
}
return 0;
}

LA 5031

链接：

代码：

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

struct node{
node *ch[2];
int r,v,s;
node(int x){ch[0] = ch[1] = NULL; r = rand(); s = 1; v = x;}
bool operator < (const node& rhs) const{return r < rhs.r;}
int cmp(int x)
{
if(x == v) return -1;
else return x < v ? 0 : 1;
}
void maintain()
{
s = 1;
if(ch[1] != NULL) s += ch[1]->s;
if(ch[0] != NULL) s += ch[0]->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
4000
(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]->r > o->r) rotate(o,d^1);
}
o->maintain();
}

void remove(node* &o,int x)
{
int d = o->cmp(x);
if(d == -1)
{
node* u = 0;
if(o->ch[0] != NULL && o->ch[1] != NULL)
{
int d2 = (o->ch[0]->r > o->ch[1]->r ? 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 maxc = 500010;
struct command{
char type;
int x,p;
}commands[maxc];

const int maxn = 20010;
const int maxm = 60010;

int n,m,weight[maxn],from[maxm],to[maxm],removed[maxm];

int pa[maxn];
int find(int x){return pa[x] != x ? pa[x] = find(pa[x]) : x;}

node* root[maxn];//treap

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 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;
}

void add_edge(int x)
{
int u = find(from[x]),v = find(to[x]);
if(u != v)
{
if(root[u]->s < root[v]->s){pa[u] = v;mergeto(root[u],root[v]);}
else {pa[v] = u;mergeto(root[v],root[u]);}
}
}

int query_cnt;
long long query_tot;
void query(int x,int k)
{
query_cnt++;
query_tot += kth(root[find(x)],k);
}

void change_weight(int x,int v)
{
int u = find(x);
remove(root[u],weight[x]);
insert(root[u],v);
weight[x] = v;
}

int main()
{
int kase = 0;
while(scanf("%d%d",&n,&m) == 2 && n)
{
for(int i = 1;i <= n;i++) scanf("%d",&weight[i]);
for(int i = 1;i <= m;i++) scanf("%d%d",&from[i],&to[i]);
memset(removed,0,sizeof(removed));

int c = 0;
for(;;)
{
char type;
int x,p = 0, v = 0;
scanf(" %c",&type);
if(type == 'E')break;
scanf("%d",&x);
if(type == 'D') removed[x] = 1;
if(type == 'Q') scanf("%d",&p);
if(type == 'C')
{
scanf("%d",&v);
p = weight[x];
weight[x] = v;
}
commands[c++] = (command){type,x,p};
}

for(int i = 1;i <= n;i++)
{
pa[i] = i;
if(root[i] != NULL) removetree(root[i]);
root[i] = new node(weight[i]);
}
for(int i = 1;i <= m;i++) if(!removed[i]) add_edge(i);

query_tot = 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_tot/(double)query_cnt);
}
return 0;
}