A string s is a prefix string of words if s can be made by concatenating the first k strings in words for some positive k no larger than words.length.

Return true if s is a prefix string of words, or false otherwise.

Example 1:

Input: s = "iloveleetcode", words = ["i","love","leetcode","apples"]
Output: true
Explanation:
s can be made by concatenating "i", "love", and "leetcode" together.

Example 2:

Input: s = "iloveleetcode", words = ["apples","i","love","leetcode"]
Output: false
Explanation:
It is impossible to make s using a prefix of arr.

Constraints:

• 1 <= words.length <= 100
• 1 <= words[i].length <= 20
• 1 <= s.length <= 1000
• words[i] and s consist of only lowercase English letters.

Solution: Concat and test

Time complexity: O(n)
Space complexity: O(n)

// Author: Huahua
class Solution {
public:
  bool isPrefixString(string s, vector<string>& words) {
    string t;
    for (const string& w : words) {
      t += w;
      if (t.length() >= s.length()) break;
    }
    return t == s;
  }
};

The post 花花酱 LeetCode 1961. Check If String Is a Prefix of Array appeared first on Huahua's Tech Road.