Pseudocode Algorithms for a few problems [closed] - algorithm

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I'm supposed to write 5 pseudocodes for algorithms below and I'm kinda stuck. The things I've done are below the tasks, I know last 3 are meaningless. Would appreciate any help or tips. Thanks
• Printing the largest number from the input
Title: Print Largest Number From Input
//works with number inputs
max=0
number= getNumber()
read number
if number == NONE
print (“NO VALID DATA”)
while number != NONE
if number > max
max = number
• Printing the largest even integer value from the input
Title: Print Largest Even Integer Number From Input
//works with even integer inputs
max=0
integer number= getNumber()
read_integer number
if number == NONE
print “NO VALID DATA”
if number % 2 == 0
print(“NO VALID DATA”)
while number != NONE && number % 2 != 0
if number > max
max = number
• Printing the sum of all input integers
Title: Print Sum of All Input Integers
int Number= getNumber()
read_integer Number
if Number == NONE
print(“NO VALID DATA”)
if Number != NONE
li.append(Number)
while li.length == n
print li[1] + li[2] + li[3] + ……. + li[n]
• Printing the arithmetic mean of all input numbers
Title: Print Arithmetic Mean of All Input Numbers
Number= getNumber()
read Number
if Number == NONE
print(“NO VALID DATA”)
if Number != NONE
li.append(Number)
while li.length == n
print li[1] + li[2] + li[3] + ……. + li[n] / n
• Printing all values greater or equal to the arithmetic mean of all input numbers
Title: Print All Values Greater Than or Equal to the Aritmetic Mean of All Input Numbers
Number= getNumber()
read Number
if Number == NONE
print(“NO VALID DATA”)
if Number != NONE
li.append(Number)
while li.length == n
arithmetic_mean = li[1] + li[2] + li[3] + ……. + li[n] / n
print(“”)


Answer 1

I'm guessing this is for class homework, so I wont provide full answers, but I'll try to help.
1. Print the largest number from the input
max = 0
// Assume that getNumber reads an input from the user and returns NONE if it is not a valid number
number = getNumber()
// If they never enter a number, give an error
if number == NONE:
print(“NO VALID DATA”)
exit() // exit the program
// Keep doing the following until number is set to NONE
while number != NONE:
if number > max:
max = number
number = getNumber()
print("The largest number is:")
print(max)
It seems like you basically have the right idea here. One thing to remember is that you have to getNumber() inside the loop. Otherwise, the value of number will never change because you only read the input once.
Note: this algorithm doesn't work if they only ever enter negative numbers. Setting max to negative infinity would fix that.
2. Print the largest even integer value from the input
This is exactly the same idea. The only change you have to make is ignoring every number that isn't even. You have the right idea for checking even-ness with the % operator.
Be careful where you make this check, though. If you check in the condition of the while loop, like you do in your code, then the loop will exit (and your program will stop) as soon as they enter an odd number. If you don't want that, then keep the loop running and just don't ever set max to be an odd number.
3. Print the sum of all input integers
It seems like your idea here is to save all the numbers they input to a list and then sum up the list at the end. That would work fine if you want to do that, but it's not necessary. Just like you kept track of a running max value, you could keep track of a running sum. Just add your the input to it each time. This is generally called the "accumulator pattern" if you want to look it up.
4. Print the arithmetic mean of all input numbers
Again, it looks like you are trying to store all the numbers in a list. Again, not necessary. Calculating the mean is just like calculating the sum except you need to divide by the number of inputs at the end. So, in addition to keeping track of the sum, you need to add an additional "accumulator" for n and just add 1 to it each time.
Also, it looks like you might be a little confused about what while does. while works just like if. It checks if a condition is true, and, if it is, it runs the code beneath it. The only difference is that while will keep running that code again and again until the condition is false. So the line while li.length == n doesn't make any sense. you haven't declared what n is before hand, so it can't make this comparison. I'm guessing you meant to do something like:
while number != NONE:
n = li.length
Here, you are assigning n to be the length of the list, instead of checking if the list length is equal to n or not.
5. Print all values greater or equal to the arithmetic mean of all input numbers
Here, we actually need to save all the inputs to a list, because we can't know what the mean is until we have seen all the numbers.
I would break this into three parts. First, just get all the input numbers and save them to a list. Then, calculate the mean of the list. Lastly, step through the list and print every value that's larger than the mean.
For part 1, just use the same pattern with a while loop that you have been since the first problem, but append number to a list instead of adding it to a sum.
For part 2, you need to calculate the sum of the list. In your code, you wrote li[1] + li[2] + li[3] + ……. + li[n]. The way you express this in code is probably with a for loop. I recommend looking up for loops for the language you are working in and seeing how they work. In some languages, you might be able to do something like this:
sum = 0
for number in list:
sum = sum + number
or, it might look like this:
sum = 0
for index in 0...list.length:
sum = sum + list[index]
For part 3, now that you have calculated the mean, you just need to loop through the numbers again and print the ones that are bigger than the mean.
for number in list:
if number > mean:
print(number)