990 - Satisfiability of Equality Equations.

Medium

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: <code>"x_i==y_i"</code> or <code>"x_i!=y_i"</code>.Here, <code>x_i</code> and <code>y_i</code> 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.

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.