BZOJ 1588 营业额统计【HNOI2002】

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题目链接：http://www.lydsy.com/JudgeOnline/problem.php?id=1588

水题，查询已有的x的前驱和后继，取差值最小即可。就是数据有点问题，具体看讨论版吧。Splay的效率捉急啊。

#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;}

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