What is the logic behind i=-1 | Sololearn: Learn to code for FREE!
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What is the logic behind i=-1

So I saw this single loop sort algorithm method and I was wondering the logic behind the line i=-1.The array only gets sorted when he does that .How did he know that is what was required,any theory behind it? https://code.sololearn.com/WmdjiruHbI8n/?ref=app

11th Nov 2022, 5:12 AM
steve Purpose
steve  Purpose - avatar
5 Answers
+ 1
The loop goes over ther whole array multiple time. After doing a value swap, the array is being validated again. Remember that i gets incremented at each loop because of the i++, setting i to -1, then increment it with i++, you are now back at 0! 1 3 2 ^ ^ 1 > 3: false 1 3 2 ^ ^ 3 > 2: true, swap them restart ( i = -1) 1 2 3 ^ ^ 1 > 2: false 1 2 3 ^ ^ 2 > 3: false all good I hope this helps :)
11th Nov 2022, 5:28 AM
Apollo-Roboto
Apollo-Roboto - avatar
+ 1
Looks like a recursive loop. Setting i = -1 after a swap forces the iteration to start from the beginning, so that the comparison and swap is made repeatedly. This way, the entire list is sorted, and the previous values are rechecked.
11th Nov 2022, 12:28 PM
Bob_Li
Bob_Li - avatar
+ 1
i = -1 cancels out the i++. it forces the iteration to start from the beginning. Since we are only swapping two values at a time, the previously swapped values might need to be swapped again. That's why it needs to go back to the starting point.
11th Nov 2022, 2:13 PM
Bob_Li
Bob_Li - avatar
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Still confused Apollo-Roboto ,considering that the original loop starts at 0.if one part is sorted ,shouldn't that be incrementing to the unsorted part?..why go back to -1
11th Nov 2022, 5:38 AM
steve Purpose
steve  Purpose - avatar
0
Ok Bob_Li thanks a lot I never knew this Apollo-Roboto thanks too .you both seem to be saying the same thing..I'll read up on it.
11th Nov 2022, 2:02 PM
steve Purpose
steve  Purpose - avatar