Replace Without Built-ins
Given a string like "amaaba", replace every occurrence of a pattern such as "aa" with another string — without using built-in string methods (no replace, find/indexOf, split).
replace_all("amaaba", "aa", "x") -> "amxba"
replace_all("aaa", "aa", "x") -> "xa" (non-overlapping, left to right)Matches are non-overlapping and found left to right, and an empty pattern leaves the string unchanged.
Hints
Hint 1
Outer pointer walks the text; at each position, an inner pointer checks the pattern character by character.
Hint 2
On a full match, emit the replacement and jump the pattern's length; otherwise emit one character and step once.