[Swift]LeetCode1078. Bigram 分詞 | Occurrences After Bigram

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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.

---

給出第一個詞 first 和第二個詞 second，考慮在某些文本 text 中可能以 "first second third" 形式出現的狀況，其中 second 緊隨 first 出現，third 緊隨 second 出現。

對於每種這樣的狀況，將第三個詞 "third" 添加到答案中，並返回答案。 

示例 1：

輸入：text = "alice is a good girl she is a good student", first = "a", second = "good"
輸出：["girl","student"]

示例 2：

輸入：text = "we will we will rock you", first = "we", second = "will"
輸出：["we","rock"] 

提示：

1. 1 <= text.length <= 1000
2. text 由一些用空格分隔的單詞組成，每一個單詞都由小寫英文字母組成
3. 1 <= first.length, second.length <= 10
4. first 和 second 由小寫英文字母組成

---

4ms

 1 class Solution {
 2     func findOcurrences(_ text: String, _ first: String, _ second: String) -> [String] {
 3       let subString = first + " " + second
 4       let arr = text.split(separator: " ")
 5       var result = [String]()
 6       for i in 0..<arr.count-2 {
 7         if arr[i] == first && arr[i+1] == second {
 8           result.append(String(arr[i+2]))
 9         }
10       }
11       return result
12     }
13 }

---

Runtime: 8 ms

Memory Usage: 21.7 MB

 1 import Foundation
 2 class Solution {
 3     func findOcurrences(_ text: String, _ first: String, _ second: String) -> [String] {
 4         if text.isEmpty {return []}
 5         var words:[String] = text.components(separatedBy: " ")
 6         var list:[String] = [String]()
 7         for i in 2..<words.count
 8         {
 9             if first == words[i-2] && second == words[i-1]
10             {
11                 list.append(words[i])
12             }
13         }
14         return list
15     }
16 }

---

8ms

 1 class Solution {
 2     func findOcurrences(_ text: String, _ first: String, _ second: String) -> [String] {
 3         var answer: [String] = []
 4         
 5         var words = Array(text.split(separator: " "))
 6         
 7         var i = 0
 8                 
 9         while (i + 2) < words.count {
10             if words[i] == first, words[i + 1] == second {
11                 answer.append(String(words[i + 2]))
12             }
13             
14             i += 1
15         }
16 
17         return answer
18     }
19 }