leetcode1027

 1 public class Solution
 2     {
 3         public int LongestArithSeqLength2(int[] A)
 4         {
 5             var maxLength = 2;
 6             var len = A.Count();
 7             for (var i = 0; i < len; i++)
 8             {
 9                 for (var j = i + 1; j < len; j++)
10                 {
11                     var curmax = 2;
12                     var target = A[i] - A[j];
13                     var next = A[j] - target;
14                     for (var k = j + 1; k < len; k++)
15                     {
16                         if (A[k] == next)
17                         {
18                             curmax++;
19                             next = A[k] - target;
20                         }
21 
22                     }
23                     maxLength = Math.Max(maxLength, curmax);
24                 }
25             }
26             return maxLength;
27         }
28     }