1078. Occurrences After Bigram

Description

Given two strings first and second, consider occurrences in some text of the form "first second third", where second comes immediately after first, and third comes immediately after second.

Return an array of all the words third for each occurrence of "first second third".

Example 1:

• Input: text = “alice is a good girl she is a good student”, first = “a”, second = “good”
• Output: [“girl”,”student”]

Example 2:

• Input: text = “we will we will rock you”, first = “we”, second = “will”
• Output: [“we”,”rock”]

Constraints:

• 1 <= text.length <= 1000
• text consists of lowercase English letters and spaces.
• All the words in text are separated by a single space.
• 1 <= first.length, second.length <= 10
• first and second consist of lowercase English letters.
• text will not have any leading or trailing spaces.

💡 Hint 1:
Split the string into words, then look at adjacent triples of words.

Submitted Code

class Solution:
    def findOcurrences(self, text: str, first: str, second: str) -> List[str]:
        words = text.split(' ')
        result = []

        for i in range(len(words)-2):
            if words[i] == first and words[i+1] == second:
                result.append(words[i+2])
        
        return result

Runtime: 0 ms | Beats 100.00%
Memory: 17.42 MB | Beats 99.58%

Other Solutions

1st

class Solution:
    def findOcurrences(self, text: str, first: str, second: str) -> List[str]:
        ans, words = [], text.split()
        for a, b, c in zip(words, words[1 :], words[2 :]):
            if (a, b) == (first, second):
                ans.append(c)
        return ans

time complexity: 𝑂(𝑛)
space complexity: 𝑂(𝑛)

zip()을 사용하는 방법도 있다.