BZOJ2151: 种树

题目：http://www.lydsy.com/JudgeOnline/problem.php?id=2151

题解：此题=数据备份。喜闻乐见挂链表。

代码：

 #include<cstdio>
 #include<cstdlib>
 #include<cmath>
 #include<cstring>
 #include<algorithm>
 #include<iostream>
 #include<vector>
 #include<map>
 #include<set>
 #include<queue>
 #include<string>
 #define inf 1000000000
 #define maxn 200000+5
 #define maxm 100000+5
 #define eps 1e-10
 #define ll long long
 #define pa pair<int,int>
 #define for0(i,n) for(int i=0;i<=(n);i++)
 #define for1(i,n) for(int i=1;i<=(n);i++)
 #define for2(i,x,y) for(int i=(x);i<=(y);i++)
 #define for3(i,x,y) for(int i=(x);i>=(y);i--)
 #define for4(i,x) for(int i=head[x],y=e[i].go;i;i=e[i].next,y=e[i].go)
 #define mod 1000000007
 using namespace std;
 inline int read()
 {
     int x=,f=;char ch=getchar();
     while(ch<''||ch>''){if(ch=='-')f=-;ch=getchar();}
     while(ch>=''&&ch<=''){x=*x+ch-'';ch=getchar();}
     return x*f;
 }
 int n,m,a[maxn],l[maxn],r[maxn];
 priority_queue<pa>q;
 int main()
 {
     freopen("input.txt","r",stdin);
     freopen("output.txt","w",stdout);
     n=read();m=read();
     if(m>n>>){printf("Error!\n");return ;}
     for1(i,n)a[i]=read(),l[i]=i-,r[i]=i+,q.push(pa(a[i],i));
     l[]=n;r[n]=;
     int ans=;
     for1(i,m)
     {
         while(!q.empty()&&q.top().first!=a[q.top().second])q.pop();
         int x=q.top().second;q.pop();
         ans+=a[x];
         a[x]=a[l[x]]+a[r[x]]-a[x];q.push(pa(a[x],x));
         a[l[x]]=a[r[x]]=inf;
         r[l[x]=l[l[x]]]=x;l[r[x]=r[r[x]]]=x;
     }
     cout<<ans<<endl;
     return ;
 }