CON-2553-Markdown-Sort-Array-exercise (#2526)

* docs: adding subject

* docs: rephrase exercice description to improve its clarity

---------

Co-authored-by: amine <aaitihia@leyton.com>

subjects/java/checkpoints/average-calc/README.md

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+## AverageCalc
+
+### Instructions
+
+Write a function named `average` in a file named `AverageCalc` java. This function takes three parameters: start, end, and step. It returns the average of the numbers between start and end with each number being greater than the previous one by the step given.
+
+### Expected Functions
+
+```java
+public class AverageCalc {
+    public static int average(int start, int end, int step) {
+        // your code here
+    }
+}
+```
+
+### Usage
+
+Here is a possible `ExerciseRunner.java` to test your function :
+
+```java
+public class ExerciseRunner {
+    public static void main(String[] args) {
+        System.out.println(AverageCalc.average(1,5,1));
+    }
+}
+```
+
+and its output :
+
+```shell
+$ javac *.java -d build
+$ java -cp build ExerciseRunner
+3
+$
+```

subjects/java/checkpoints/digitlen/README.md

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+## Digitlen
+
+### Instructions
+
+In a file named `Digitlen.java` write a function `digitlen` that returns the count of digits in the number passed as a parameter.
+
+### Expected Functions
+
+```java
+public class Digitlen {
+    public static int digitlen(long number) {
+        // your code here
+    }
+}
+```
+
+### Usage
+
+Here is a possible `ExerciseRunner.java` to test your function :
+
+```java
+public class ExerciseRunner {
+    public static void main(String[] args) {
+        System.out.println(Digitlen.digitlen(9989898878));
+    }
+}
+```
+
+and its output :
+
+```shell
+$ javac *.java -d build
+$ java -cp build ExerciseRunner
+10
+$
+```

subjects/java/checkpoints/multiplication-table/README.md

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+## MultiplicationTable
+
+### Instructions
+
+In a file named `MultiplicationTable.java` write a function `generate` which takes a number as a parameter, and prints the multiplication table for this number.
+
+### Expected Functions
+
+```java
+public class MultiplicationTable {
+    public static void generate(int num) {
+        // your code here
+    }
+}
+```
+
+### Usage
+
+Here is a possible `ExerciseRunner.java` to test your function :
+
+```java
+public class ExerciseRunner {
+    public static void main(String[] args) {
+        MultiplicationTable.generate(5);
+    }
+}
+```
+
+and its output :
+
+```shell
+$ javac *.java -d build
+$ java -cp build ExerciseRunner
+5 x 1 = 5
+5 x 2 = 10
+5 x 3 = 15
+5 x 4 = 20
+5 x 5 = 25
+5 x 6 = 30
+5 x 7 = 35
+5 x 8 = 40
+5 x 9 = 45
+5 x 10 = 50
+$
+```

subjects/java/checkpoints/sort-array/README.md

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+## SortArray
+
+### Instructions
+
+In a file named `SortArray.java` write a function `sort` that returns the given array, specified in the parameters, sorted in ascending order.
+
+### Expected Functions
+
+```java
+public class SortArray {
+    public static Integer[] sort(Integer[] args) {
+        // your code here
+    }
+}
+```
+
+### Usage
+
+Here is a possible `ExerciseRunner.java` to test your function :
+
+```java
+import java.io.*;
+import java.util.Arrays;
+
+public class ExerciseRunner {
+    public static void main(String[] args) throws IOException {
+        System.out.println(Arrays.toString(SortArray.sort(new Integer[]{4, 2, 1, 3})));
+    }
+}
+```
+
+and its output :
+
+```shell
+$ javac *.java -d build
+$ java -cp build ExerciseRunner
+[1, 2, 3, 4]
+$
+```

subjects/java/checkpoints/strlen/README.md

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+## Strlen
+
+### Instructions
+
+In a file named `Strlen.java` write a function `strlen` that returns the length of the string passed as a parameter.
+
+### Expected Functions
+
+```java
+public class Strlen {
+    public static int strlen(String s) {
+        // your code here
+    }
+}
+```
+
+### Usage
+
+Here is a possible `ExerciseRunner.java` to test your function :
+
+```java
+public class ExerciseRunner {
+    public static void main(String[] args) {
+        System.out.println(Strlen.strlen("Hello World !"));
+    }
+}
+```
+
+and its output :
+
+```shell
+$ javac *.java -d build
+$ java -cp build ExerciseRunner
+13
+$
+```