Why does my Python spell checker only process the last word?

Add temporary output inside the outer loop to see which word is being searched and what `lo`, `hi`, and `mid` contain. That will show whether the file-reading loop is collecting every word and whether the binary search is running for each one. If only the final word is processed, the likely cause is that the outer loop or the list updates are indented outside the loop.

There is also an off-by-one issue in the search. With `while lo < hi`, the final remaining dictionary item may never be checked. Use `while lo <= hi`, set `mid = (lo + hi) // 2`, and move the bounds with `lo = mid + 1` or `hi = mid - 1`. After the loop, check the `found` flag before classifying the word.

First, make sure the indentation is preserved when sharing and running the code. In Python, indentation determines whether the loops and list updates are inside the outer loop. The search should run once for every word in `firstLst`, and the result should be appended only after that word's binary search finishes.

Use the `found` flag to decide which list receives the word. Right now the code appears to append the word to `present` and `absent` regardless of whether it was found. The structure should be roughly: `for word in firstLst:`, perform the binary search, then `if found: present.append(word)`, otherwise `absent.append(word)`. Also print both lists after the outer loop, not during every iteration.