Difference between revisions of "Sum Scan Assignment"

From CSE425S Wiki
Jump to navigation Jump to search
Line 11: Line 11:
 
  fun sum_scan(xs : int list) : int list
 
  fun sum_scan(xs : int list) : int list
  
which produces a list whose values are each the sum of values in <code>xs</code> up to and including the value at its location.
+
which produces a list whose values are the [https://en.wikipedia.org/wiki/Running_total running totals] of the values in <code>xs</code>.
  
 
===Example [1,2,3,4,5,6,7,8]===
 
===Example [1,2,3,4,5,6,7,8]===

Revision as of 04:54, 21 January 2022

Background

Prefix sum on Wikipedia

Code to Implement

file: src/main/sml/warmup_sum_scan/sum_scan.sml Smlnj-logo.png
functions: sum_scan

sum_scan

Write a function

fun sum_scan(xs : int list) : int list

which produces a list whose values are the running totals of the values in xs.

Example [1,2,3,4,5,6,7,8]

For example:

sum_scan([1,2,3,4,5,6,7,8])

would produce:

[1,3,6,10,15,21,28,36]
xs 1 2 3 4 5 6 7 8
sum_scan(xs) 1 3 6 10 15 21 28 36

Example [131,231,425]

For example:

sum_scan([131,231,425])

would produce:

[131, 362, 787]
xs 131 231 425
sum_scan(xs) 131 362 787

Test

file: unit_test_sum_scan.sml
source folder: src/test/sml/warmup_sum_scan