Need help understanding basic pseudocode algorithm problems

Question

May I trouble anyone to help me understand how this sort of pseudocode algorithm works and how it arrived at the correct answer? Any help would be greatly appreciated.

Answer 1

These are questions with traps in them. It is testing whether you really look closely to every aspect of the code for both question 6 and question 7:

Question 6

The first code can be expressed in JavaScript as follows:

function Find2(s, n) {
    let EleFound = s[0]
    for (let i = n-1; i >= 0; i--) {
        if (s[i] > EleFound) {
            EleFound = i
        }
    }
    return EleFound
}

let result = Find2([3, 15, 7, 9], 4);
console.log(result);

When you run it, you'll see it outputs 0. Once you see it, it is obvious, but the line EleFound = i is assigning the index, not s[i]! And as the index i is decreasing to zero, and s[1] is greater than the initial value of EleFound, EleFound will get the value 1, not 15! And in the last iteration it will get assigned 0, because s[0] is greater than 1(!).

Question 7

The second code can be run as:

function AddMul5(A, n) {
    let sum = A[0]
    for (let i = 1; i <= n-1; i++) {
        sum = sum + i
    }
    return sum
}

let result = AddMul5([3, 5, 7, 9], 5);
console.log(result);

The output is 13. Did you spot the trap here? It is quite similar...

Hints:

which values from A are used in this sum?

Is A[1] used at all?