LCT维护最大生成树。。。。。然而这种题目比赛的时候根本不敢写。。。
#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; }