LeetCode #139 - Word Break: Given a string s and a dictionary of strings wordDict, return true if s can be segmented into a space-separated sequence of one or more dictionary words. You may assume the dictionary does not contain duplicate words.\n**Input:** s = "leetcode", wordDict = ["leet","code"]\n**Output:** true\n**Input:** s = "applepenapple", wordDict = ["apple","pen"]\n**Output:** true\n**Constraints:** 1 <= s.length <= 300\n1 <= wordDict.length <= 1000\n1 <= wordDict[i].length <= 20

LeetCode #293 - Flip Game Given a string that contains only these two characters: "+" and "-", you need to reverse the signs of the string's segments. A segment is defined as consecutive characters of the same type. You need to generate all possible states after flipping the signs of segments. When you flip a segment, you change the '+'s to '-'s and vice versa. Return the list of all possible states in any order. **Input:** "++--" **Output:** [ "++++", "+--+", "-++-", "-+--", "--++", "----" ] **Constraints:** - The input string will only contain characters '+' and '-'. - The length of the string will be in the range [1, 20].

Can you describe a time when you had to design a backend system to handle a significant scale or load? What architecture did you decide on, and why?