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# 0990. Satisfiability of Equality Equations

<https://leetcode.com/problems/satisfiability-of-equality-equations>

## Description

You are given an array of strings `equations` that represent relationships between variables where each string `equations[i]` is of length `4` and takes one of two different forms: `"xi==yi"` or `"xi!=yi"`.Here, `xi` and `yi` are lowercase letters (not necessarily different) that represent one-letter variable names.

Return `true` *if it is possible to assign integers to variable names so as to satisfy all the given equations, or* `false` *otherwise*.

**Example 1:**

```
**Input:** equations = ["a==b","b!=a"]
**Output:** false
**Explanation:** If we assign say, a = 1 and b = 1, then the first equation is satisfied, but not the second.
There is no way to assign the variables to satisfy both equations.
```

**Example 2:**

```
**Input:** equations = ["b==a","a==b"]
**Output:** true
**Explanation:** We could assign a = 1 and b = 1 to satisfy both equations.
```

**Example 3:**

```
**Input:** equations = ["a==b","b==c","a==c"]
**Output:** true
```

**Example 4:**

```
**Input:** equations = ["a==b","b!=c","c==a"]
**Output:** false
```

**Example 5:**

```
**Input:** equations = ["c==c","b==d","x!=z"]
**Output:** true
```

**Constraints:**

* `1 <= equations.length <= 500`
* `equations[i].length == 4`
* `equations[i][0]` is a lowercase letter.
* `equations[i][1]` is either `'='` or `'!'`.
* `equations[i][2]` is `'='`.
* `equations[i][3]` is a lowercase letter.

## ac

```java
```