//DP入门题状态转移方程很容易想到 //关键是构建pre数组，多少有点像KMP里面构建的next数组 #include 
     
      #include 
      
       #define MAX 50100int a[MAX],pre[MAX],dp[MAX];int n;int main(){        int i,j,T,max;        scanf("%d",&T);        while(T--)        {                scanf("%d",&n);                pre[1]=0;  dp[1]=0;                scanf("%d",&a[1]);                max=0;                for(i=2; i<=n; i++)                {                        scanf("%d",&a[i]);                        if(a[i]
       
        =a[j] ; j=pre[j]) ;                                pre[i]=j;                                if(!pre[i])  dp[i]=0;                                else         dp[i]=dp[pre[i]]+1;                        }                        max=dp[i]>max?dp[i]:max;                }//              for(i=1; i<=n; i++) printf("%d ",pre[i]); printf("\n");//              for(i=1; i<=n; i++) printf("%d ",dp[i]);  printf("\n");                printf("%d\n",max);        }        return 0;}