Arrays - General Questions

What is the output of the following code?

a = [2, -1, 3, -4, 5]
best = cur = a[0]
for x in a[1:]:
    cur = max(x, cur + x)
    best = max(best, cur)
print(best)

Prefix sums let you answer a range-sum query in:

What is the output of the following code?

a = [3, 8, 1, 9, 4]
best = a[0]
for x in a:
    if x > best:
        best = x
print(best)