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O(n)
n = length(string)

Python | Java

	# O(n^2)
	def appendNtimesUsingStringConcat(c: str, n: int) -> str:
	out_str = ""
	for i in range(n):
	out_str += c # O(s) where s = length(out_str)
	return out_str
	# O(n)
	def appendNtimesUsingStringJoin(c: str, n: int) -> str:
	list = []
	for i in range(n):
	list.append(c); # O(1)
	return "".join(list)

view raw StringJoin.py hosted with ❤ by GitHub

	// O(n^2)
	public void appendNtimesUsingStringConcat(char c, int n) {
	String str = "";
	for (int i = 0; i < n; i++) {
	str += c; // O(s) where s = length(str)
	}
	return str;
	}
	// O(n)
	public void appendNtimesUsingStringBuilder(char c, int n) {
	StringBuilder sb = new StringBuilder();
	for (int i = 0; i < n; i++) {
	sb.append(c); // O(1)
	}
	return sb.toString();
	}

view raw UseStringBuilder.java hosted with ❤ by GitHub

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