【动态树】 HDOJ 5398 GCD Tree

#include <bits/stdc++.h>
using namespace std;

#define mp(x, y) make_pair(x, y)
const int maxn = 100005;
const int maxm = 300005;
const int INF = 0x3f3f3f3f * 2;

struct node *null;
struct node
{
int size, rev, t1, t2;
pair<int, node*> Min, cMin;
node *fa, *ch[2];

void init()
{
size = rev = 0;
fa = ch[0] = ch[1] = null;
}

inline bool d()
{
return fa->ch[1] == this;
}

inline bool isroot()
{
return fa == null || fa->ch[0] != this && fa->ch[1] != this;
}

inline void setc(node *p, int d)
{
ch[d] = p;
p->fa = this;
}

inline void pushup()
{
size = ch[0]->size + ch[1]->size + 1;
Min = cMin;
if(ch[0] != null) Min = min(Min, ch[0]->Min);
if(ch[1] != null) Min = min(Min, ch[1]->Min);
}

inline void flip()
{
if(this == null) return;
swap(ch[0], ch[1]);
rev ^= 1;
}

inline void pushdown()
{
if(rev) {
ch[0]->flip();
ch[1]->flip();
rev = 0;
}
}

inline void go()
{
if(!isroot()) fa->go();
pushdown();
}

void rot()
{
node *f = fa, *ff = fa->fa;
int c = d(), cc = fa->d();
f->setc(ch[!c], c);
this->setc(f, !c);
if(ff->ch[cc] == f) ff->setc(this, cc);
else this->fa = ff;
f->pushup();
}

node* splay()
{
go();
while(!isroot()) {
if(!fa->isroot()) d() == fa->d() ? fa->rot() : rot();
rot();
}
pushup();
return this;
}

node* access()
{
for(node *p = this, *q = null; p != null; q = p, p = p->fa) {
p->splay()->setc(q, 1);
p->pushup();
}
return splay();
}

inline void makeroot()
{
access()->flip();
}

node* getroot() {
node *x;
for(x = access(); x->pushdown(), x->ch[0] != null; x = x->ch[0]);
return x;
}

void cut()
{
access();
ch[0]->fa = null;
ch[0] = null;
pushup();
}

void cut(node *o)
{
makeroot();
o->cut();
}

void link(node *p)
{
makeroot();
fa = p;
}
}*Node[maxn], pool[maxm], *tail;

int res[maxn];
vector<int> vec[maxn];
int n;

pair<int, node*> query(node *a, node *b)
{
a->access();
for(a = null; b != null; a = b, b = b->fa) {
b->splay();
if(b->fa == null) return min(b->ch[1]->Min, a->Min);
b->setc(a, 1);
b->pushup();
}
}

node* newnode()
{
node *p = tail++;
p->fa = p->ch[0] = p->ch[1] = null;
p->size = p->rev = 0;
p->Min = p->cMin = mp(INF, p);
return p;
}

void init()
{
tail = pool;
null = newnode();
for(int i = 1; i <= n; i++) Node[i] = newnode();

for(int i = n; i >= 1; i--)
for(int j = i + i; j <= n; j += i)
vec[j].push_back(i);

int ans = 0;
for(int i = 2; i <= n; i++) {
int t = vec[i][0];
node *p = newnode();
p->t1 = i, p->t2 = t;
p->cMin = p->Min = mp(t, p);
p->link(Node[i]);
p->link(Node[t]);
ans += t;

for(int j = 1; j < vec[i].size(); j++) {
t = vec[i][j];
pair<int, node*> tpair = query(Node[i], Node[t]);
if(tpair.first >= t) continue;
ans -= tpair.first;
ans += t;

p = tpair.second;

int t1 = p->t1;
int t2 = p->t2;

p->cut(Node[t1]);
p->cut(Node[t2]);

p->init();
p->t1 = i, p->t2 = t;
p->Min = p->cMin = mp(t, p);
p->link(Node[i]);
p->link(Node[t]);
}
res[i] = ans;
}
}

int main()
{
n = 100000;
init();
int t;
while(scanf("%d", &t) != EOF) {
printf("%d\n", res[t]);
}

return 0;
}