HYSBZ 1588 营业额统计 伸展树

题目链接:http://www.lydsy.com/JudgeOnline/problem.php?id=1588
题意:每次查找集合中一个key对于给定的tmp满足 |tmp-key|最小,将tmp加入集合
维护每次的最小差值
第一道伸展树题,大神的模板很好用

代码:

#include <bits/stdc++.h>
#define sf scanf
#define pf printf
using namespace std;
const int maxn = 100000 + 50;
typedef long long LL;
const LL INF = 10000000000;
int sroot,root,tot,ch[maxn][2],fa[maxn];
LL key[maxn];


/**
**  NewNode
*/
void NewNode(int& rt,int FA,LL k){
    rt = tot++;
    fa[rt] = FA;
    key[rt] = k;
    ch[rt][0] = ch[rt][1] = 0;
}
/**  kind 0 for zig
**   kind 1 for zag
*/
void rotate(int rt,int kind){
    int prt = fa[rt];
    ch[prt][kind] = ch[rt][!kind];
    fa[ch[rt][!kind]] = prt;
    if(fa[prt] != sroot){
        ch[ fa[ prt ] ][ (ch[ fa[ prt ] ][1] == prt) ] = rt;
    }
    fa[rt] = fa[prt];
    ch[rt][!kind] = prt;
    fa[prt] = rt;
}

/** goal sroot for splay rt to root
**  kind 0 left son to zig operation
**  kind 1 right son to zag operation
*/
void Splay(int rt,int goal){
    while(fa[rt] != goal){
        //父节点就是目标节点 直接进行一次旋转
        if(fa[fa[rt]] == goal)
            rotate(rt,ch[fa[rt]][1] == rt);
        else{
            int prt = fa[rt];
            int kind = (ch[fa[prt]][1] == prt);
            if(ch[prt][kind] == rt){    //一字型
                rotate(rt,kind);
            }
            else{                       //之字型
                rotate(rt,!kind);
                rotate(rt,kind);
            }
        }
    }
    if(goal == sroot) root = rt;
}

int Insert(LL k){
    int rt = root;
    while(ch[rt][key[rt] < k]){
        if(key[rt] == k){
            Splay(rt,sroot);
            return 0;
        }
        rt = ch[rt][key[rt] < k];
    }
    NewNode(ch[rt][key[rt] < k],rt,k);
    Splay(ch[rt][key[rt] < k],sroot);
    return 1;
}

LL Find_Pre(){
    int rt = ch[root][0];
    if(rt == 0) return INF;
    while(ch[rt][1]) rt = ch[rt][1];
    return key[rt];
}
LL Find_Next(){
    int rt = ch[root][1];
    if(rt == 0) return INF;
    while(ch[rt][0]) rt = ch[rt][0];
    return key[rt];
}

LL fabs(LL k){
    return  k > 0 ? k : -k;
}
int main(){
    int n;
    while( ~sf("%d",&n) ){
        sroot = root = 0,fa[0] = 0;
        ch[root][0] = ch[root][1] = 0;
        LL tmp,ans = 0;
        tot = 1;
        sf("%lld",&tmp);Insert(tmp);
//        pf("Start:\n");
        ans += tmp;
        for(int i = 1;i < n;++i){
            sf("%lld",&tmp);
            if(!Insert(tmp)) continue;
            else{
                ans += min(fabs(tmp - Find_Next()),fabs(tmp - Find_Pre()));
            }
//            pf("tmp = %lld key %lld\n",tmp,key[root]);
        }
        pf("%lld\n",ans);
    }
    return 0;
}