Merge branch 'update-tests-palindrome-calculator' of https://github.com/jagdish-15/java into update-tests-palindrome-calculator

Merging with origin

Author: jagdish-15

docs/TESTS.md

@@ -81,6 +81,20 @@ Good luck! Have fun!
 
    _(Don't worry about the tests failing, at first, this is how you begin each exercise.)_
 
+   If you get the following error:
+
+   ```sh
+   ./gradlew: Permission denied
+   ```
+
+   Then the file is missing the execute permission. To fis this, run:
+
+   ```sh
+   chmod +x ./gradlew
+   ```
+
+   And now you should be able to run the previous command.
+
 4. Solve the exercise. Find and work through the `instructions.append.md` guide ([view on GitHub][hello-world-tutorial]).
 
 Good luck! Have fun!

exercises/concept/salary-calculator/.meta/src/reference/java/SalaryCalculator.java

@@ -8,11 +8,11 @@ public int bonusMultiplier(int productsSold) {
         return productsSold < 20 ? 10 : 13;
     }
 
-    public double bonusForProductsSold (int productsSold) {
+    public double bonusForProductsSold(int productsSold) {
         return productsSold * bonusMultiplier(productsSold);
     }
 
-    public double finalSalary (int daysSkipped, int productsSold) {
+    public double finalSalary(int daysSkipped, int productsSold) {
         double finalSalary = 1000.0 * salaryMultiplier(daysSkipped) + bonusForProductsSold(productsSold);
         return finalSalary > 2000.0 ? 2000.0 : finalSalary;
     } 

exercises/practice/bob/.meta/config.json

@@ -7,6 +7,7 @@
     "austinlyons",
     "c-thornton",
     "FridaTveit",
+    "jagdish-15",
     "jmrunkle",
     "jtigger",
     "kytrinyx",

exercises/practice/bob/.meta/tests.toml

@@ -1,6 +1,13 @@
-# This is an auto-generated file. Regular comments will be removed when this
-# file is regenerated. Regenerating will not touch any manually added keys,
-# so comments can be added in a "comment" key.
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
 
 [e162fead-606f-437a-a166-d051915cea8e]
 description = "stating something"
@@ -64,6 +71,7 @@ description = "alternate silence"
 
 [66953780-165b-4e7e-8ce3-4bcb80b6385a]
 description = "multiple line question"
+include = false
 
 [5371ef75-d9ea-4103-bcfa-2da973ddec1b]
 description = "starting with whitespace"
@@ -76,3 +84,7 @@ description = "other whitespace"
 
 [12983553-8601-46a8-92fa-fcaa3bc4a2a0]
 description = "non-question ending with whitespace"
+
+[2c7278ac-f955-4eb4-bf8f-e33eb4116a15]
+description = "multiple line question"
+reimplements = "66953780-165b-4e7e-8ce3-4bcb80b6385a"

exercises/practice/bob/src/test/java/BobTest.java

@@ -152,13 +152,6 @@ public void alternateSilence() {
                 .isEqualTo("Fine. Be that way!");
     }
 
-    @Disabled("Remove to run test")
-    @Test
-    public void multipleLineQuestion() {
-        assertThat(bob.hey("\nDoes this cryogenic chamber make me look fat?\nNo."))
-                .isEqualTo("Whatever.");
-    }
-
     @Disabled("Remove to run test")
     @Test
     public void startingWithWhitespace() {
@@ -187,4 +180,11 @@ public void nonQuestionEndingWithWhiteSpace() {
                 .isEqualTo("Whatever.");
     }
 
+    @Disabled("Remove to run test")
+    @Test
+    public void multipleLineQuestion() {
+        assertThat(bob.hey("\nDoes this cryogenic chamber make\n me look fat?"))
+                .isEqualTo("Sure.");
+    }
+
 }

exercises/practice/change/.approaches/config.json

@@ -0,0 +1,21 @@
+{
+  "introduction": {
+    "authors": [
+      "jagdish-15"
+    ]
+  },
+  "approaches": [
+    {
+      "uuid": "d0b615ca-3a02-4d66-ad10-e0c513062189",
+      "slug": "dynamic-programming",
+      "title": "Dynamic Programming Approach",
+      "blurb": "Use dynamic programming to find the most efficient change combination.",
+      "authors": [
+        "jagdish-15"
+      ],
+      "contributors": [
+        "kahgoh"
+      ]
+    }
+  ]
+}

exercises/practice/change/.approaches/dynamic-programming/content.md

@@ -0,0 +1,68 @@
+# Dynamic Programming Approach
+
+```java
+import java.util.List;
+import java.util.ArrayList;
+
+class ChangeCalculator {
+    private final List<Integer> currencyCoins;
+
+    ChangeCalculator(List<Integer> currencyCoins) {
+        this.currencyCoins = currencyCoins;
+    }
+
+    List<Integer> computeMostEfficientChange(int grandTotal) {
+        if (grandTotal < 0) 
+            throw new IllegalArgumentException("Negative totals are not allowed.");
+
+        List<List<Integer>> coinsUsed = new ArrayList<>(grandTotal + 1);
+        coinsUsed.add(new ArrayList<Integer>());
+
+        for (int i = 1; i <= grandTotal; i++) {
+            List<Integer> bestCombination = null;
+            for (int coin: currencyCoins) {
+                if (coin <= i && coinsUsed.get(i - coin) != null) {
+                    List<Integer> currentCombination = new ArrayList<>(coinsUsed.get(i - coin));
+                    currentCombination.add(0, coin);
+                    if (bestCombination == null || currentCombination.size() < bestCombination.size())
+                        bestCombination = currentCombination;
+                }
+            }
+            coinsUsed.add(bestCombination);
+        }
+
+        if (coinsUsed.get(grandTotal) == null)
+            throw new IllegalArgumentException("The total " + grandTotal + " cannot be represented in the given currency.");
+
+        return coinsUsed.get(grandTotal);
+    }
+}
+```
+
+The **Dynamic Programming (DP)** approach is an efficient way to solve the problem of making change for a given total using a list of available coin denominations.
+It minimizes the number of coins needed by breaking down the problem into smaller subproblems and solving them progressively.
+
+## Explanation
+
+### Initialize Coins Usage Tracker
+
+- If the `grandTotal` is negative, an exception is thrown immediately.
+- We create a list `coinsUsed`, where each index `i` stores the most efficient combination of coins that sum up to the value `i`.
+- The list is initialized with an empty list at index `0`, as no coins are needed to achieve a total of zero.
+
+### Iterative Dynamic Programming
+
+- For each value `i` from 1 to `grandTotal`, we explore all available coin denominations to find the best combination that can achieve the total `i`.
+- For each coin, we check if it can be part of the solution (i.e., if `coin <= i` and `coinsUsed[i - coin]` is a valid combination).
+- If so, we generate a new combination by adding the current coin to the solution for `i - coin`. We then compare the size of this new combination with the existing best combination and keep the one with fewer coins.
+
+### Result
+
+- After processing all values up to `grandTotal`, the combination at `coinsUsed[grandTotal]` will represent the most efficient solution.
+- If no valid combination exists for `grandTotal`, an exception is thrown.
+
+## Time and Space Complexity
+
+The time complexity of this approach is **O(n * m)**, where `n` is the `grandTotal` and `m` is the number of available coin denominations. This is because we iterate over all coin denominations for each amount up to `grandTotal`.
+  
+The space complexity is **O(n)** due to the list `coinsUsed`, which stores the most efficient coin combination for each total up to `grandTotal`.

exercises/practice/change/.approaches/dynamic-programming/snippet.txt

@@ -0,0 +1,8 @@
+class ChangeCalculator {
+    private final List<Integer> currencyCoins;
+
+    ChangeCalculator(List<Integer> currencyCoins) {
+        this.currencyCoins = currencyCoins;
+    }
+    // computeMostEfficientChange method
+}

exercises/practice/change/.approaches/introduction.md

@@ -0,0 +1,55 @@
+# Introduction  
+
+There is an idiomatic approach to solving "Change."  
+You can use [dynamic programming][dynamic-programming] to calculate the minimum number of coins required for a given total.
+
+## General guidance
+
+The key to solving "Change" is understanding that not all totals can be reached with the available coin denominations.
+The solution needs to figure out which totals can be achieved and how to combine the coins optimally.
+
+## Approach: Dynamic Programming
+
+```java
+import java.util.List;
+import java.util.ArrayList;
+
+class ChangeCalculator {
+    private final List<Integer> currencyCoins;
+
+    ChangeCalculator(List<Integer> currencyCoins) {
+        this.currencyCoins = currencyCoins;
+    }
+
+    List<Integer> computeMostEfficientChange(int grandTotal) {
+        if (grandTotal < 0) 
+            throw new IllegalArgumentException("Negative totals are not allowed.");
+
+        List<List<Integer>> coinsUsed = new ArrayList<>(grandTotal + 1);
+        coinsUsed.add(new ArrayList<Integer>());
+
+        for (int i = 1; i <= grandTotal; i++) {
+            List<Integer> bestCombination = null;
+            for (int coin: currencyCoins) {
+                if (coin <= i && coinsUsed.get(i - coin) != null) {
+                    List<Integer> currentCombination = new ArrayList<>(coinsUsed.get(i - coin));
+                    currentCombination.add(0, coin);
+                    if (bestCombination == null || currentCombination.size() < bestCombination.size())
+                        bestCombination = currentCombination;
+                }
+            }
+            coinsUsed.add(bestCombination);
+        }
+
+        if (coinsUsed.get(grandTotal) == null)
+            throw new IllegalArgumentException("The total " + grandTotal + " cannot be represented in the given currency.");
+
+        return coinsUsed.get(grandTotal);
+    }
+}
+```
+
+For a detailed look at the code and logic, see the full explanation in the [Dynamic Programming Approach][approach-dynamic-programming].
+
+[approach-dynamic-programming]: https://exercism.org/tracks/java/exercises/change/approaches/dynamic-programming
+[dynamic-programming]: https://en.wikipedia.org/wiki/Dynamic_programming

exercises/practice/complex-numbers/.docs/instructions.md

@@ -1,29 +1,100 @@
 # Instructions
 
-A complex number is a number in the form `a + b * i` where `a` and `b` are real and `i` satisfies `i^2 = -1`.
+A **complex number** is expressed in the form `z = a + b * i`, where:
 
-`a` is called the real part and `b` is called the imaginary part of `z`.
-The conjugate of the number `a + b * i` is the number `a - b * i`.
-The absolute value of a complex number `z = a + b * i` is a real number `|z| = sqrt(a^2 + b^2)`. The square of the absolute value `|z|^2` is the result of multiplication of `z` by its complex conjugate.
+- `a` is the **real part** (a real number),
 
-The sum/difference of two complex numbers involves adding/subtracting their real and imaginary parts separately:
-`(a + i * b) + (c + i * d) = (a + c) + (b + d) * i`,
-`(a + i * b) - (c + i * d) = (a - c) + (b - d) * i`.
+- `b` is the **imaginary part** (also a real number), and
 
-Multiplication result is by definition
-`(a + i * b) * (c + i * d) = (a * c - b * d) + (b * c + a * d) * i`.
+- `i` is the **imaginary unit** satisfying `i^2 = -1`.
 
-The reciprocal of a non-zero complex number is
-`1 / (a + i * b) = a/(a^2 + b^2) - b/(a^2 + b^2) * i`.
+## Operations on Complex Numbers
 
-Dividing a complex number `a + i * b` by another `c + i * d` gives:
-`(a + i * b) / (c + i * d) = (a * c + b * d)/(c^2 + d^2) + (b * c - a * d)/(c^2 + d^2) * i`.
+### Conjugate
 
-Raising e to a complex exponent can be expressed as `e^(a + i * b) = e^a * e^(i * b)`, the last term of which is given by Euler's formula `e^(i * b) = cos(b) + i * sin(b)`.
+The conjugate of the complex number `z = a + b * i` is given by:
 
-Implement the following operations:
+```text
+zc = a - b * i
+```
 
-- addition, subtraction, multiplication and division of two complex numbers,
-- conjugate, absolute value, exponent of a given complex number.
+### Absolute Value
 
-Assume the programming language you are using does not have an implementation of complex numbers.
+The absolute value (or modulus) of `z` is defined as:
+
+```text
+|z| = sqrt(a^2 + b^2)
+```
+
+The square of the absolute value is computed as the product of `z` and its conjugate `zc`:
+
+```text
+|z|^2 = z * zc = a^2 + b^2
+```
+
+### Addition
+
+The sum of two complex numbers `z1 = a + b * i` and `z2 = c + d * i` is computed by adding their real and imaginary parts separately:
+
+```text
+z1 + z2 = (a + b * i) + (c + d * i)
+        = (a + c) + (b + d) * i
+```
+
+### Subtraction
+
+The difference of two complex numbers is obtained by subtracting their respective parts:
+
+```text
+z1 - z2 = (a + b * i) - (c + d * i)
+        = (a - c) + (b - d) * i
+```
+
+### Multiplication
+
+The product of two complex numbers is defined as:
+
+```text
+z1 * z2 = (a + b * i) * (c + d * i)
+        = (a * c - b * d) + (b * c + a * d) * i
+```
+
+### Reciprocal
+
+The reciprocal of a non-zero complex number is given by:
+
+```text
+1 / z = 1 / (a + b * i)
+      = a / (a^2 + b^2) - b / (a^2 + b^2) * i
+```
+
+### Division
+
+The division of one complex number by another is given by:
+
+```text
+z1 / z2 = z1 * (1 / z2)
+        = (a + b * i) / (c + d * i)
+        = (a * c + b * d) / (c^2 + d^2) + (b * c - a * d) / (c^2 + d^2) * i
+```
+
+### Exponentiation
+
+Raising _e_ (the base of the natural logarithm) to a complex exponent can be expressed using Euler's formula:
+
+```text
+e^(a + b * i) = e^a * e^(b * i)
+              = e^a * (cos(b) + i * sin(b))
+```
+
+## Implementation Requirements
+
+Given that you should not use built-in support for complex numbers, implement the following operations:
+
+- **addition** of two complex numbers
+- **subtraction** of two complex numbers
+- **multiplication** of two complex numbers
+- **division** of two complex numbers
+- **conjugate** of a complex number
+- **absolute value** of a complex number
+- **exponentiation** of _e_ (the base of the natural logarithm) to a complex number