📝 hierarchical-parentheses description

hierarchical-parentheses/README.md

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+## Describing the logic
+
+To write mathematical equations we used 3 types of parenthesis: `(), [], {}` and these were always hierarchical like this: `{[()]}`, always in this order. And to go even further we would reuse the curly braces like this `{ { { [ ( ) ] } } }`. It's like [Matryoshka doll](https://en.wikipedia.org/wiki/Matryoshka_doll) from Russia. :)
+
+An example would be: `{(4 + 1) * { 5 * [( 5 ^ 2 - 4 ^ 2 ) * 2 ]}} / 2`. (where `5^2` means 5 to the power of 2).
+
+## Describing the challenge
+
+We need an application that would take a mathematical equation as string for input and return a boolean response representing the validity of the parenthesis ordering.
+
+Some valid equations for which the application would return `true`:
+    - `5 * 5`
+    - `(4 + 1) * 2`
+    - `(4 + 1) * [(2 - 4) / (2 + 2)]`
+    - `{(4 + 1) * { 5 * [( 5 ^ 2 - 4 ^ 2 ) * 2 ]}} / 2`
+
+Some invalid equations for which the application would return `false`:
+    - `(4 + 1) * 2)`
+    - `[4 + 1] * 2`
+    - `4 * ([2 - 4] / [2 + 2])`
+    - `4 * {(2 - 4) / (2 + 2)}`
+    - `([4 * [1 + 2] - 1])`