Generate All Substrings of a String

Problem Generate all contiguous substrings of a string — n(n+1)/2 of them.

Input / Output

• Input: string s. Output: all substrings (list them; clarify if duplicates should collapse).

Constraints

• |s| <= ~100 (output is O(n^2) strings totaling O(n^3) chars — state this before coding).

Example

• "abc" → a, ab, abc, b, bc, c.

Expected approach

• Double loop over (start, end) pairs emitting s.substring(start, end) — O(n^2) substrings, O(n^3) total character work (each substring copy is O(n); note the copy cost, and StringBuilder-extension per start as the micro-optimization). Dedupe via a set when required. This is usually a warm-up probing loop-boundary precision and complexity articulation — get the n(n+1)/2 count and the substring-vs-subsequence distinction (2^n) crisp.