fix(QuickSort): use low instead of hardcoded 0 in left recursive call#2
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The left recursive call passed a hardcoded 0 as the lower bound instead of low, so every left-partition call re-sorted the array from index 0 rather than from the start of the current sub-problem. The result stayed correct (the [0, low-1] prefix is already in place) but recursion work blew up to O(n^2): on a descending array of 2000 elements the buggy version makes 1,001,001 quickSort invocations vs 3,999 after the fix, which is what can drive the reported StackOverflowError on large inputs. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Fixes #1
The left recursive call in
quickSortused a hardcoded0as the lower bound instead oflow:Every left-partition call re-sorted the array from index 0 rather than from the start of the current sub-problem. The output stayed correct (the
[0, low-1]prefix is already in place), but recursion work blew up to O(n²). On a descending array of 2000 elements the buggy version makes 1,001,001quickSortinvocations vs 3,999 after the fix — which is what can drive the reported StackOverflowError on large inputs.Validated by compiling and running the sort on several arrays (including descending and a 2000-element descending case); all sort correctly, and recursion depth is back to expected.
Thanks to @UsaaryanByte07 for the clear report and root-cause trace.