codeforce 987c

题目链接：点击打开链接

n^2的动态规划，每次查询在i之前的2值，更新i的3值，在i之前的1值，更新i的2值。初始化时将所有元素的1值都置为c【i】。

#include<iostream>
#include<cstdio>
#include<vector>
#include<set>
#include<map>
#include<string.h>
#include<cmath>
#include<algorithm>
#include<queue>
#include<stack>
#define LL long long
#define mod 1000000007
#define inf 0x3f3f3f3f
#define sqr(a) (a)*(a)
#define For(i,m,n) for(int i=m;i<=n;i++)
#define Dor(i,n,m) for(int i=n;i>=m;i--)
#define lan(a,b) memset(a,b,sizeof(a))
#define maxn 100010

using namespace std;

LL dp[3010][4];

int main()
{
    int n;
    while(~scanf("%d",&n))
    {
        int s[3010],c[3010];
        lan(dp,inf);
        For(i,1,n)
        scanf("%d",&s[i]);
        For(i,1,n)
        scanf("%d",&c[i]);
        For(i,1,n)
        dp[i][1]=c[i];
        LL minn=inf;
        For(i,1,n)
        For(j,1,i-1)
        {
            if(s[j]<s[i])
            {
                dp[i][2]=min(dp[i][2],dp[j][1]+c[i]);
                dp[i][3]=min(dp[i][3],dp[j][2]+c[i]);
                //printf("dp %d=%lld %lld\n",i,dp[i][2],dp[i][3]);
                minn=min(minn,dp[i][3]);
            }
        }
        if(minn==inf)
            printf("-1\n");
        else
            printf("%lld\n",minn);
    }
    return 0;
}