for (int r = 3; r < dataGrid.Rows.Count; r++)
{
    for (int c = 2; c <= 4; c++)
    {
         var ssq = new List<int>(3) {Convert.ToInt32(listGrid[r - 2,c])};
         var sq = new List<int>(3) {Convert.ToInt32(listGrid[r - 1, c])};
         var bq = new List<int>(3) {Convert.ToInt32(listGrid[r, c])};
    }
}

                for (int r = 4; r < dataGrid.Rows.Count; r++)
                {
                    List<int> ssq = new List<int>(3);
                    ssq.Add(Convert.ToInt32(listGrid[r - 2, 2]));
                    ssq.Add(Convert.ToInt32(listGrid[r - 2, 3]));
                    ssq.Add(Convert.ToInt32(listGrid[r - 2, 4]));

                    foreach (int val in ssq)
                    {
                        listGrid[r, 16] = val;
                    }
                }

------解决方案--------------------
for (int c = 2; c <= 4; c++)
{
 List<int> ssq = new List<int>();
 ssq.Add(Convert.ToInt32(listGrid[2, c]));
 if (ssq.Contains(3))
 {
   listGrid[2, 16] = "yes"; // 坐标写死，循环就看最后个值了
 }
 else
 {
   listGrid[2, 16] = "no";
 }
}