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Hard
2661
Weekly Contest 415 Q4
Segment Tree
Array
String
Binary Search
Dynamic Programming
String Matching
Hash Function
Rolling Hash

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Description

You are given an array of strings words and a string target.

A string x is called valid if x is a prefix of any string in words.

Return the minimum number of valid strings that can be concatenated to form target. If it is not possible to form target, return -1.

 

Example 1:

Input: words = ["abc","aaaaa","bcdef"], target = "aabcdabc"

Output: 3

Explanation:

The target string can be formed by concatenating:

  • Prefix of length 2 of words[1], i.e. "aa".
  • Prefix of length 3 of words[2], i.e. "bcd".
  • Prefix of length 3 of words[0], i.e. "abc".

Example 2:

Input: words = ["abababab","ab"], target = "ababaababa"

Output: 2

Explanation:

The target string can be formed by concatenating:

  • Prefix of length 5 of words[0], i.e. "ababa".
  • Prefix of length 5 of words[0], i.e. "ababa".

Example 3:

Input: words = ["abcdef"], target = "xyz"

Output: -1

 

Constraints:

  • 1 <= words.length <= 100
  • 1 <= words[i].length <= 5 * 104
  • The input is generated such that sum(words[i].length) <= 105.
  • words[i] consists only of lowercase English letters.
  • 1 <= target.length <= 5 * 104
  • target consists only of lowercase English letters.

Solutions

Solution 1

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