poj 1390 动态规划

思路：

黑书的例题

#include<iostream>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<cstdio>
#define Maxn 210
using namespace std;
int dp[Maxn][Maxn][Maxn],col[Maxn],len[Maxn],pre[Maxn],aper[Maxn],after[Maxn],vi[Maxn];
int main()
{
    int t,n,i,j,x,k,Case=0;
    int cnt=0;
    scanf("%d",&t);
    while(t--){
        memset(dp,0,sizeof(dp));
        memset(pre,0,sizeof(pre));
        memset(len,0,sizeof(len));
        memset(aper,0,sizeof(aper));
        cnt=0;
        scanf("%d",&n);
        for(i=1;i<=n;i++){
            scanf("%d",&x);
            if(x!=col[cnt])
                col[++cnt]=x,len[cnt]=1,pre[cnt]=aper[x],aper[x]=cnt;
            else
                len[cnt]++;
        }
        memset(vi,0,sizeof(vi));
        for(i = cnt; i >= 1; i--){
            if(vi[i]) continue;
            after[i] = 0;
            int tmp = i;
            for(j = i-1; j >= 1; j--)
                if(col[j] == col[tmp]){
                    after[j] = after[tmp] + len[tmp];
                    tmp = j;
                    vi[j--] = true;
                }
        }
        int l;
        for(l=0;l<=cnt;l++){
            for(i=1;i+l<=cnt;i++){
                j=i+l;
                for(k=0;k<=after[j];k++){
                    dp[i][j][k]=dp[i][j-1][0]+(len[j]+k)*(len[j]+k);
                    int p=pre[j];
                    while(p>=i){
                    dp[i][j][k]=max(dp[i][j][k], dp[i][p][k+len[j]]+dp[p+1][j-1][0]);
                    p=pre[p];
                    }
                }
            }
        }
        printf("Case %d: %d\n",++Case,dp[1][cnt][0]);
    }
    return 0;
}