Searching & max / min

Linear search

• A linear search looks at each item in turn until it finds the target.
• It is a named standard method in the syllabus.
• Use a loop and remember when you find a match.

nums = [4, 9, 2, 7]
target = 9
found = False
for n in nums:
    if n == target:
        found = True
print(found)         # True

Finding the maximum

• Start by assuming the first item is the biggest.
• Then check the rest; if one is bigger, remember it instead.

nums = [4, 9, 2, 7]
biggest = nums[0]
for n in nums:
    if n > biggest:
        biggest = n
print(biggest)       # 9

Finding the minimum

• The same idea, but keep the smallest value seen so far.

nums = [4, 9, 2, 7]
smallest = nums[0]
for n in nums:
    if n < smallest:
        smallest = n
print(smallest)      # 2

In the exam: standard methods

• Linear search and finding maximum / minimum / average are named in section 7.

Found ← FALSE
FOR i ← 1 TO 4
    IF Number[i] = Target THEN
        Found ← TRUE
    ENDIF
NEXT i

Common mistakes

• Linear search checks each item in turn until it finds the target.
• For max or min, start from the first item, then compare the rest against it.

Now you try

• Loop through the list to search or compare.
• Press Check answer to test your code.