Word Break II
Difficulty: Hard
Category: DSA
Topics: Array, Hash Table, String, Dynamic Programming, Backtracking, Trie, Memoization
Asked at: Facebook, Amazon, Bloomberg, ByteDance, Google, Microsoft
Given a string `s` and a dictionary of strings `wordDict`, add spaces in `s` to construct a sentence where each word is a valid dictionary word. Return all such possible sentences in **any order**.
**Note** that the same word in the dictionary may be reused multiple times in the segmentation.
**Example 1:**
**Input:** s = "catsanddog", wordDict = ["cat","cats","and","sand","dog"]
**Output:** ["cats and dog","cat sand dog"]
```
**Example 2:**
**Input:** s = "pineapplepenapple", wordDict = ["apple","pen","applepen","pine","pineapple"]
**Output:** ["pine apple pen apple","pineapple pen apple","pine applepen apple"]
**Explanation:** Note that you are allowed to reuse a dictionary word.
```
**Example 3:**
**Input:** s = "catsandog", wordDict = ["cats","dog","sand","and","cat"]
**Output:** []
```
**Constraints:**
- `1 <= s.length <= 20`
- `1 <= wordDict.length <= 1000`
- `1 <= wordDict[i].length <= 10`
- `s` and `wordDict[i]` consist of only lowercase English letters.
- All the strings of `wordDict` are **unique**.
- Input is generated in a way that the length of the answer doesn't exceed 105.