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CCC Python Course

Loop-and-count problems (J2 pattern)

Stage
3
Module
M3.2
Lessons
1

In this module

  • Read multiple items in a loop and accumulate a count or total.
  • Initialize a counter before the loop and update it inside.
  • Use the final count to make a decision or produce output.

Before this module

M1.6while loops, break/continue, sentinels and EOFM2.4Accumulator patterns

Lessons

  1. 1Loop-and-count problems (J2 pattern)

Practice

Try these on the judges. Each link opens the problem on WMOJ or DMOJ.

  1. 2022 J2
    Fergusonball Ratings (opens on WMOJ in a new tab) WMOJ

    Process two lines of data per player and flag those meeting a condition.

  2. 2020 J3
    Art (opens on DMOJ in a new tab) DMOJ

    Scan a comma-separated line of numbers, tracking the minimum and maximum as you go.

    Why DMOJ: A running-minimum-and-maximum scan, the same one-pass shape as this lesson's counters.

  3. 2019 J2
    Time to Decompress (opens on DMOJ in a new tab) DMOJ

    Expand a run-length compressed string and process the result in a loop.

    Why DMOJ: A one-pass scan with a running total, in the same style as this lesson's examples.