feat: kata/basic-math-add-or-subtract (#845)

* docs: kata description

* feat: kata/basic-math-add-or-subtract

---------

Co-authored-by: ParanoidUser <[email protected]>

Author: github-actions[bot]

kata/7-kyu/basic-math-add-or-subtract/README.md

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+# [Basic Math (Add or Subtract)](https://www.codewars.com/kata/basic-math-add-or-subtract "https://www.codewars.com/kata/5809b62808ad92e31b000031")
+
+In this kata, you will do addition and subtraction on a given string. The return value must be also a string.
+
+**Note:** the input will not be empty.
+
+## Examples
+
+```
+"1plus2plus3plus4" --> "10"
+"1plus2plus3minus4" --> "2"
+```

kata/7-kyu/basic-math-add-or-subtract/main/Kata.java

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+import static java.util.stream.Stream.of;
+
+interface Kata {
+  static String calculate(String str) {
+    return of(str.replace("minus", "plus-").split("plus")).mapToInt(Integer::parseInt).sum() + "";
+  }
+}

kata/7-kyu/basic-math-add-or-subtract/test/CalculateExampleTest.java

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+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+
+class CalculateExampleTest {
+  @ParameterizedTest
+  @CsvSource(textBlock = """
+      1plus2plus3plus4, 10
+      1minus2minus3minus4, -8
+      1plus2plus3minus4, 2
+      1minus2plus3minus4, -2
+      1plus2minus3plus4minus5, -1
+      """)
+  void sample(String equation, String result) {
+    assertEquals(result, Kata.calculate(equation));
+  }
+}

kata/7-kyu/index.md

@@ -44,6 +44,7 @@
 - [Averages of numbers](averages-of-numbers "57d2807295497e652b000139")
 - [Balanced Number (Special Numbers Series #1) ](balanced-number-special-numbers-series-number-1 "5a4e3782880385ba68000018")
 - [Basic Calculator](basic-calculator "5296455e4fe0cdf2e000059f")
+- [Basic Math (Add or Subtract)](basic-math-add-or-subtract "5809b62808ad92e31b000031")
 - [Basic Sequence Practice](basic-sequence-practice "5436f26c4e3d6c40e5000282")
 - [Basics - Generators #1](basics-generators-number-1 "5636840bd87777688b00006c")
 - [Batman Quotes](batman-quotes "551614eb77dd9ee37100003e")