question

According to your description, the following code might be useful:

         public static bool IsTrue(int[] array) 
         {
             bool re = true;
             for (int i = 0; i < array.Length-1; i++)
             {
                 if (array[i] < array[i + 1]) 
                 {
                     re = false;
                     break;
                 }
             }
             return re;
         }

But the third example also seems to be True, which is decreasing.

Update:

         public static bool IsTrue(List<int> array) 
         {
             bool re = true;
             for (int i = 0; i < array.Count-1; i++)
             {
                 if (array[i] < array[i + 1]) 
                 {
                     re = false;
                     break;
                 }
             }
             return re;
         }

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