Question

A programmer develops the procedure hasElevenEleven(), which should return true if it ever finds a 1 next to a 1 somewhere. For example, hasElevenEleven([7, 1, 1]) should return true, but hasElevenEleven([1, 7, 1]) should return false.

PROCEDURE hasElevenEleven(numbers) { i ← 1 REPEAT UNTIL (i = (LENGTH(numbers) - 1)) { IF (numbers[i] = 1 AND numbers[i + 1] = 1) { RETURN true } i ← i + 1 } RETURN false }
The programmer tests it with hasElevenEleven([1, 0, 1, 1, 0]) and sees that it does indeed return true.
Can the programmer conclude that the procedure works correctly for all inputs?

Answer 1

While the procedure hasElevenEleven() appears to work for a specific test case, it starts checking from the second element due to the initial value of i being set to 1.

Step-by-step explanation:

The question is whether the procedure hasElevenEleven() works correctly for all inputs. The procedure should return true if it encounters two adjacent 1s in an array. From the example given, the procedure appears to work correctly for the input [1, 0, 1, 1, 0]. However, based on the provided code, the loop initializes i to 1, which means it starts checking from the second element of the array, not the first. This means that the procedure would not correctly detect a pair of 1s at the beginning of the array, such as in [1, 1, 7]. Consequently, to make the procedure work correctly for all inputs, the initial value of i should be set to 0 instead of 1. After adjusting this, comprehensive testing with diverse scenarios is recommended to ensure the procedure's reliability for all possible inputs.

The programmer cannot conclude that the procedure works correctly for all inputs based on the provided information. The fact that the programmer tested the procedure with the input hasElevenEleven([1, 0, 1, 1, 0]) and it returned true does not guarantee that it will work for all inputs. It is important to test the procedure with different inputs, including corner cases and edge cases, to ensure its correctness.

This would result in the procedure failing to detect a pair of 1s at the start of an array. The programmer needs to correct the initial value of i and perform further testing.