# LeetCode 1078. Occurrences After Bigram

## Description

https://leetcode.com/problems/occurrences-after-bigram/

Given words `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`.

For each such occurrence, add “`third`” to the answer, and return the answer.

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"]
```

Note:

1. `1 <= text.length <= 1000`
2. `text` consists of space separated words, where each word consists of lowercase English letters.
3. `1 <= first.length, second.length <= 10`
4. `first` and `second` consist of lowercase English letters.

## Explanation

We can convert text to a list of words and search the “second” string in the list. If we find the “second” string in the list, we can check if the previous word in the list is the “first” string, if it is, we add the next word after the “second” string. Keep searching, until no more text words.

## Python Solution

``````class Solution:
def findOcurrences(self, text: str, first: str, second: str) -> List[str]:
results = []

text = text.split()

i = 0

while i < len(text) - 2:

if text[i] == first and text[i + 1] == second:
results.append(text[i + 2])

i += 1

return results
``````
• Time Complexity: O(N).
• Space Complexity: O(N).