# LeetCode 734. Sentence Similarity

## Description

https://leetcode.com/problems/sentence-similarity/

We can represent a sentence as an array of words, for example, the sentence `"I am happy with leetcode"` can be represented as `arr = ["I","am",happy","with","leetcode"]`.

Given two sentences `sentence1` and `sentence2` each represented as a string array and given an array of string pairs `similarPairs` where `similarPairs[i] = [xi, yi]` indicates that the two words `xi` and `yi` are similar.

Return `true` if `sentence1` and `sentence2` are similar, or `false` if they are not similar.

Two sentences are similar if:

• They have the same length (i.e. the same number of words)
• `sentence1[i]` and `sentence2[i]` are similar.

Notice that a word is always similar to itself, also notice that the similarity relation is not transitive. For example, if the words `a` and `b` are similar and the words `b` and `c` are similar, `a` and `c` are not necessarily similar.

Example 1:

```Input: sentence1 = ["great","acting","skills"], sentence2 = ["fine","drama","talent"], similarPairs = [["great","fine"],["drama","acting"],["skills","talent"]]
Output: true
Explanation: The two sentences have the same length and each word i of sentence1 is also similar to the corresponding word in sentence2.
```

Example 2:

```Input: sentence1 = ["great"], sentence2 = ["great"], similarPairs = []
Output: true
Explanation: A word is similar to itself.
```

Example 3:

```Input: sentence1 = ["great"], sentence2 = ["doubleplus","good"], similarPairs = [["great","doubleplus"]]
Output: false
Explanation: As they don't have the same length, we return false.
```

Constraints:

• `1 <= sentence1.length, sentence2.length <= 1000`
• `1 <= sentence1[i].length, sentence2[i].length <= 20`
• `sentence1[i]` and `sentence2[i]` consist of lower-case and upper-case English letters.
• `0 <= similarPairs.length <= 1000`
• `similarPairs[i].length == 2`
• `1 <= xi.length, yi.length <= 20`
• `xi` and `yi` consist of lower-case and upper-case English letters.
• All the pairs `(xi,yi)` are distinct.

## Explanation

First compare the length of two sentences. Then check if words in sequences are in pairs.

## Python Solution

``````class Solution:
def areSentencesSimilar(self, sentence1: List[str], sentence2: List[str], similarPairs: List[List[str]]) -> bool:
if len(sentence1) != len(sentence2):
return False

pairs_dict = defaultdict(set)
for pair in similarPairs: