Add boundary checks to quicksort partition to prevent out-of-range access

[Copilot]

The partition function's inner loops lacked boundary checks, allowing indices to traverse beyond the [left, right] subarray being partitioned. This caused incorrect comparisons with elements outside the partition scope, particularly when the pivot was a minimum or maximum value.

Changes

• Added i <= right check to prevent forward traversal beyond partition boundary
• Added j >= left check to prevent backward traversal beyond partition boundary
• Created test suite covering edge cases: pivot as min/max, duplicates, and sorted arrays

Example

// Before: i and j could access elements outside [left, right]
while (items[i] < pivot) {
    i++;
}

// After: boundary checks ensure indices stay within partition range
while (i <= right && items[i] < pivot) {
    i++;
}

The conditions use short-circuit evaluation, so array access only occurs when indices are in bounds.

Original prompt

quickSort breaks when the pivot is a minimum or maximum of the array. Fix it.

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.