Implement memcpy / Reverse a String In-Place

Problem Implement memcpy that also handles overlapping source and destination regions correctly (i.e. memmove semantics), and reverse a C string in place.

Input / Output

• Input: destination pointer, source pointer, byte count n; and a null-terminated string.
• Output: n bytes copied correctly even under overlap; the string reversed in place.

Constraints

• Handle overlapping ranges and the null terminator; no extra buffer.

Example

• memmove within an overlapping buffer; reverse("hello") → "olleh".