BZOJ 1588 营业额统计【HNOI2002】

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

int n,cnt;

const int inf = 2147483645;

long long ans = 0;

struct Node {
int val;
Node *fa,*ch[2];
}*root,*null,T[10000000+10];

Node* Newnode(Node *f,int val) {
T[cnt].fa = f;T[cnt].val = val;T[cnt].ch[0] = T[cnt].ch[1] = null;return &T[cnt++];
}

void Rotate(Node *u) {
Node *x = u -> fa,*y = x -> fa;int v = u == x -> ch[1];
u -> fa = y;if(y != null)y -> ch[x == y -> ch[1]] = u;
x -> ch[v] =  u -> ch[v^1];if(u -> ch[v^1] != null)u -> ch[v^1] -> fa = x;
x -> fa = u;u -> ch[v^1] = x;
}

void Splay(Node *u,Node *f) {
Node *x;
for(;(x = u -> fa) != f;Rotate(u))if(x -> fa != f)Rotate((u == x -> ch[1]) == (x == x -> fa -> ch[1]) ? x : u);
if(f == null)root = u;
}

void init() {
null = Newnode(null,0);root = Newnode(null,inf);root -> ch[0] = Newnode(root,-inf);
}

Node* Find_front(int x) {
Node *u = root,*ret;int rr = -inf-1;
while(u != null) {
if(u -> val > x)u = u -> ch[0];
else {
if(u -> val > rr) {
rr = u -> val;ret = u;
}
u = u -> ch[1];
}
}
return ret;
}

Node* Find_back(int x) {
Node *u = root,*ret;int rr = inf+1;
while(u != null) {
if(u -> val < x)u = u -> ch[1];
else {
if(u -> val < rr) {
rr = u -> val;ret = u;
}
u = u -> ch[0];
}
}
return ret;
}

long long Get(int x) {
Node *L = Find_front(x),*R = Find_back(x);
long long ret;
if(L -> val == -inf)ret = R -> val - 1LL * x;
else if(R -> val == inf)ret = 1LL * x - L -> val;
else ret = min(R -> val - 1LL * x,1LL * x - L -> val);
if(ret != 0) {
Splay(R,null);Splay(L,root);Node *u = (root -> ch[0] -> ch[1] = Newnode(root -> ch[0],x));Splay(u,null);
}
return ret;
}

int main() {
init();int x;
scanf("%d",&n);
scanf("%d",&x);
ans += x;root -> ch[0] -> ch[1] = Newnode(root -> ch[0],x);
for(int i = 1; i < n; i++) {
if(scanf("%d",&x) == EOF)x = 0;
ans += Get(x);
}
printf("%lld\n",ans);
return 0;
}