1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
| #include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<vector>
using namespace std;
#define int ll
#define REP(i,e,s) for(register int i=e; i<=s; i++)
#define DREP(i,e,s) for(register int i=e; i>=s; i--)
#define ll long long
#define DE(...) fprintf(stderr,__VA_ARGS__)
#define DEBUG(a) DE("DEBUG: %d\n",a)
#define file(a) freopen(a".in","r",stdin);freopen(a".out","w",stdout)
int read() {
int x=0,f=1,ch=getchar();
while(ch>'9'||ch<'0'){if(ch=='-')f=-1;ch=getchar();}
while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
return x*f;
}
const int MAXN=100000+10;
int s[MAXN],p[MAXN],c[MAXN],dp[MAXN];
int x(int i) {return s[i]*c[i];}
int y(int i) {return dp[i-1]+s[i]*c[i]*c[i]-2*s[i]*c[i];}
double calc1(int i,int j) {
return 1.0*(y(i)-y(j))/(x(i)-x(j));
}
int calc2(int i,int j) {
return dp[j-1]+s[i]*(c[i]-c[j]+1)*(c[i]-c[j]+1);
}
vector<int> stack[MAXN];
signed main() {
int n=read();
REP(i,1,n) s[i]=read(),c[i]=c[p[s[i]]]+1,p[s[i]]=i;
REP(i,1,n) {
while (stack[s[i]].size()>=2&&calc1(stack[s[i]][stack[s[i]].size()-2],i)>=calc1(stack[s[i]][stack[s[i]].size()-2],stack[s[i]][stack[s[i]].size()-1])) stack[s[i]].pop_back();
stack[s[i]].push_back(i);
while (stack[s[i]].size()>=2&&calc2(i,stack[s[i]][stack[s[i]].size()-1])<=calc2(i,stack[s[i]][stack[s[i]].size()-2])) stack[s[i]].pop_back();
dp[i]=calc2(i,stack[s[i]].back());
}
printf("%lld\n",dp[n]);
return 0;
}
|
