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Predict the output: list slicing
🔮 Predict the outputTopic: listsDifficulty: easyNo login needed
The snippet
Three slices of the same five-element list. Every one of them is governed by a single rule — slices include the start, exclude the stop — plus the meaning of a negative start and a step. Write all three printed lines before revealing.
nums = [10, 20, 30, 40, 50]
print(nums[1:4])
print(nums[-2:])
print(nums[::2])Your prediction
Type exactly what this program prints — one line per print() call:
The output
[20, 30, 40]
[40, 50]
[10, 30, 50]Line-by-line explanation
nums = [10, 20, 30, 40, 50]
Five elements at indexes 0–4. Keep both index rows in mind: 0..4 from the front, -5..-1 from the back.print(nums[1:4])
Half-open interval: start 1 included, stop 4 excluded — indexes 1, 2, 3 →[20, 30, 40]. Length is stop − start = 3.print(nums[-2:])
Start −2 translates to 5 + (−2) = 3; omitted stop means 'to the end' — indexes 3, 4 →[40, 50].print(nums[::2])
Both bounds omitted, step 2: take index 0, skip one, repeat — indexes 0, 2, 4 →[10, 30, 50].
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