[USACO16OPEN]248

传送门啦

分析：

一个裸的区间dp，我们只需要注意合并的时候并不像2048那样加倍，每次都加1就好了

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
using namespace std;
const int maxn = 250;

inline int read(){
    int f = 1 , x = 0;
    char ch = getchar();
    while(ch > '9' || ch < '0') {if(ch == '-') f = -1; ch = getchar();}
    while(ch >= '0' && ch <= '9'){x = (x << 1) + (x << 3) + ch - '0'; ch = getchar();}
    return x * f;
}

int n,m;
int f[maxn][maxn],ans;

int main(){
    n = read();
    for(int i=1;i<=n;i++)  f[i][i] = read() , ans = max(ans , f[i][i]);
    for(int i=n;i>=1;i--)
       for(int j=i+1;j<=n;j++)
          for(int k=i;k<=j;k++)
             if(f[i][k] == f[k+1][j]){
                f[i][j] = max(f[i][j] , f[i][k] + 1);
                ans = max(ans , f[i][j]);
            }
    printf("%d",ans);
    return 0;
}