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：
1 #include<cstdio> 2 #include<cstdlib> 3 #include<cmath> 4 #include<cstring> 5 #include<algorithm> 6 #include<iostream> 7 #include<vector> 8 #include<map> 9 #include<set> 10 #include<queue> 11 #include<string> 12 #define inf 1000000000 13 #define maxn 50000+5 14 #define maxm 100000+5 15 #define eps 1e-10 16 #define ll long long 17 #define pa pair<int,int> 18 #define for0(i,n) for(int i=0;i<=(n);i++) 19 #define for1(i,n) for(int i=1;i<=(n);i++) 20 #define for2(i,x,y) for(int i=(x);i<=(y);i++) 21 #define for3(i,x,y) for(int i=(x);i>=(y);i--) 22 #define for4(i,x) for(int i=head[x],y=e[i].go;i;i=e[i].next,y=e[i].go) 23 #define mod 1000000007 24 using namespace std; 25 inline int read() 26 { 27 int x=0,f=1;char ch=getchar(); 28 while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();} 29 while(ch>='0'&&ch<='9'){x=10*x+ch-'0';ch=getchar();} 30 return x*f; 31 } 32 int n,a[maxn],b[maxn],f[maxn],next[maxn],last[maxn]; 33 ll g[maxn],t[maxn]; 34 int main() 35 { 36 freopen("input.txt","r",stdin); 37 freopen("output.txt","w",stdout); 38 n=read(); 39 for1(i,n+2)b[i]=inf; 40 for2(i,2,n+1)a[i]=read()-i; 41 a[1]=-inf;a[n+2]=inf-1; 42 n+=2; 43 for1(i,n) 44 { 45 f[i]=upper_bound(b+1,b+n+1,a[i])-b; 46 b[f[i]]=a[i]; 47 } 48 cout<<n-f[n]<<endl; 49 for3(i,n,1)next[i]=last[f[i]],last[f[i]]=i; 50 memset(g,127,sizeof(g)); 51 for1(i,n) 52 { 53 if(f[i]==1){g[i]=0;continue;} 54 t[i]=0; 55 for3(j,i-1,last[f[i]-1])t[j]=t[j+1]+abs(a[j]-a[i]); 56 for(int j=last[f[i]-1];j;j=next[j])if(a[j]<=a[i]) 57 { 58 if(j+1==i){g[i]=min(g[i],g[j]);continue;} 59 ll tot=0; 60 for2(k,j,i-1) 61 { 62 tot+=abs(a[j]-a[k]); 63 g[i]=min(g[i],g[j]+tot+t[k+1]); 64 } 65 } 66 } 67 cout<<g[n]<<endl; 68 return 0; 69 }