Word Break

Description

Given a non-empty string s and a dictionary wordDict containing a list of non-empty words, determine if s can be segmented into a space-separated sequence of one or more dictionary words.

Note:

• The same word in the dictionary may be reused multiple times in the segmentation.
• You may assume the dictionary does not contain duplicate words.

Example 1:

Input: s = "leetcode", wordDict = ["leet", "code"]
Output: true
Explanation: Return true because "leetcode" can be segmented as "leet code".

Example 2:

Input: s = "applepenapple", wordDict = ["apple", "pen"]
Output: true
Explanation: Return true because "applepenapple" can be segmented as "apple pen apple".
             Note that you are allowed to reuse a dictionary word.

Example 3:

Input: s = "catsandog", wordDict = ["cats", "dog", "sand", "and", "cat"]
Output: false

Solution(javascript)

const wordBreak = (s, wordDict = []) => {
  const memo = {}
  const aux = (current = '') => {
    if (memo[current] !== undefined) {
      return memo[current]
    }
    if (current === s) {
      return true
    }
    if (s.indexOf(current) === -1) {
      return false
    }
    memo[current] = wordDict.some(word => aux(current + word))
    return memo[current]
  }
  return aux('')
}