让最长的凸序列称为LCS； N> 1的最小长度为2。下面的算法不言自明。

Lets call the longest convex sequence as LCS; The minimum possible length for N>1 is 2. The algo below is self explanatory.

int LCS[N];
LCS[0] = 1; LCS[1] =2 ;

for(i=2;i<N;i++)
{
   LCS[i] = 2;
   for(j=1;j<i;j++)
   {
       for(k=0;k<j;k++)
       {
           if(LCS[j]-1 == LCS[k] && A[j] < (A[k] + A[i])/2 )
               LCS[i] = max( LCS[i], 1+LCS[j]);
       }
   }
}