BZOJ1049: [HAOI2006]数字序列

题目：http://www.lydsy.com/JudgeOnline/problem.php?id=1049

题解：

ydc的题解：http://pan.baidu.com/share/link?uk=2651016602&shareid=1490516411

第二问比较神？考场上敢去猜结论？

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 50000+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,a[maxn],b[maxn],f[maxn],next[maxn],last[maxn];
 ll g[maxn],t[maxn];
 int main()
 {
     freopen("input.txt","r",stdin);
     freopen("output.txt","w",stdout);
     n=read();
     for1(i,n+)b[i]=inf;
     for2(i,,n+)a[i]=read()-i;
     a[]=-inf;a[n+]=inf-;
     n+=;
     for1(i,n)
     {
         f[i]=upper_bound(b+,b+n+,a[i])-b;
         b[f[i]]=a[i];
     }
     cout<<n-f[n]<<endl;
     for3(i,n,)next[i]=last[f[i]],last[f[i]]=i;
     memset(g,,sizeof(g));
     for1(i,n)
     {
         if(f[i]==){g[i]=;continue;}
         t[i]=;
         for3(j,i-,last[f[i]-])t[j]=t[j+]+abs(a[j]-a[i]);
         for(int j=last[f[i]-];j;j=next[j])if(a[j]<=a[i])
         {
             if(j+==i){g[i]=min(g[i],g[j]);continue;}
             ll tot=;
             for2(k,j,i-)
             {
                 tot+=abs(a[j]-a[k]);
                 g[i]=min(g[i],g[j]+tot+t[k+]);
             }
         }
     }
     cout<<g[n]<<endl;
     return ;
 }