feat(curriculum): add n-queens lab (#62420)

Co-authored-by: Dario <105294544+Dario-DC@users.noreply.github.com>

client/i18n/locales/english/intro.json

@@ -4743,7 +4743,12 @@
           "In this lab, you will implement the Depth-First Search Algorithm."
         ]
       },
-      "lab-n-queens-problem": { "title": "", "intro": [""] },
+      "lab-n-queens-problem": {
+        "title": "Implement the N-Queens Problem",
+        "intro": [
+          "In this lab, you will implement a solution for the N-Queens problem."
+        ]
+      },
       "review-graphs-and-trees": {
         "title": "Graphs and Trees Review",
         "intro": [

client/src/pages/learn/full-stack-developer/lab-n-queens-problem/index.md

@@ -0,0 +1,9 @@
+---
+title: Introduction to the Implement the N-Queens Algorithm
+block: lab-n-queens-problem
+superBlock: full-stack-developer
+---
+
+## Introduction to the Implement the N-Queens Algorithm
+
+In this lab, you will implement a solution for the N-Queens problem.

curriculum/challenges/english/blocks/lab-n-queens-problem/68dbc6b7e8f794a2ae69bc74.md

@@ -0,0 +1,178 @@
+---
+id: 68dbc6b7e8f794a2ae69bc74
+title: Implement the N-Queens Algorithm
+challengeType: 27
+dashedName: step-1
+---
+
+# --description--
+
+The N-Queens problem asks you to place N queens on an N×N chessboard so that no two queens attack each other (no two share a row, column, or diagonal). 
+
+For example, if there is a 4x4 board, one valid arrangement is:
+
+```md
+[1, 3, 0, 2]
+```
+
+That means that in row 0, the queen is placed in column 1; in row 1, the queen is placed in column 3; in row 2, the queen is placed in column 0; and in row 3, the queen is placed in column 2.
+
+Visually, this arrangement looks like:
+
+```md
+. Q . .
+. . . Q
+Q . . .
+. . Q .
+```
+
+Where `Q` represents a queen and `.` represents an empty square.
+
+In this lab, you will implement the N-Queens problem solver using the depth-first search approach.
+
+
+**Objective**: Fulfill the user stories below and get all the tests to pass to complete the lab.
+
+**User Stories:**
+
+1. You should have a function named `dfs_n_queens`.
+2. The function should accept exactly one argument: an integer `n`.
+3. If `n` is less than `1`, the function should return an empty list (`[]`).
+4. The function should return a list of solutions; each solution is itself a list of length `n`, where the element at index `i` is the column index (0-based) of the queen in row `i`.
+
+# --hints--
+
+You should have a function named `dfs_n_queens` that takes one argument.
+
+```js
+({ test: () => runPython(`
+  import inspect
+  assert inspect.isfunction(dfs_n_queens)
+  sig = inspect.signature(dfs_n_queens)
+  assert len(sig.parameters) == 1
+`) })
+```
+
+If `n` is less than `1`, the function should return an empty list.
+
+```js
+({ test: () => runPython(`
+  assert dfs_n_queens(0) == []
+  assert dfs_n_queens(-1) == []
+  assert dfs_n_queens(-5) == []
+`) })
+```
+
+The function should return a list of solutions, where each solution is a list of length `n`.
+
+```js
+({ test: () => runPython(`
+  result = dfs_n_queens(4)
+  assert isinstance(result, list)
+  for solution in result:
+    assert isinstance(solution, list)
+    assert len(solution) == 4
+`) })
+```
+
+`dfs_n_queens(1)` should return `[[0]]`.
+
+```js
+({ test: () => runPython(`
+  assert dfs_n_queens(1) == [[0]]
+  assert dfs_n_queens(5) == [[0, 2, 4, 1, 3], [0, 3, 1, 4, 2], [1, 3, 0, 2, 4], [1, 4, 2, 0, 3], [2, 0, 3, 1, 4], [2, 4, 1, 3, 0], [3, 0, 2, 4, 1], [3, 1, 4, 2, 0], [4, 1, 3, 0, 2], [4, 2, 0, 3, 1]]
+`) })
+```
+
+`dfs_n_queens(2)` should return `[]`.
+
+```js
+({ test: () => runPython(`
+  assert dfs_n_queens(2) == []
+  assert dfs_n_queens(5) == [[0, 2, 4, 1, 3], [0, 3, 1, 4, 2], [1, 3, 0, 2, 4], [1, 4, 2, 0, 3], [2, 0, 3, 1, 4], [2, 4, 1, 3, 0], [3, 0, 2, 4, 1], [3, 1, 4, 2, 0], [4, 1, 3, 0, 2], [4, 2, 0, 3, 1]]
+`) })
+```
+
+`dfs_n_queens(3)` should return `[]`.
+
+```js
+({ test: () => runPython(`
+  assert dfs_n_queens(3) == []
+  assert dfs_n_queens(5) == [[0, 2, 4, 1, 3], [0, 3, 1, 4, 2], [1, 3, 0, 2, 4], [1, 4, 2, 0, 3], [2, 0, 3, 1, 4], [2, 4, 1, 3, 0], [3, 0, 2, 4, 1], [3, 1, 4, 2, 0], [4, 1, 3, 0, 2], [4, 2, 0, 3, 1]]
+`) })
+```
+
+`dfs_n_queens(4)` should return `[[1, 3, 0, 2], [2, 0, 3, 1]]`.
+
+```js
+({ test: () => runPython(`
+  assert dfs_n_queens(4) == [[1, 3, 0, 2], [2, 0, 3, 1]]
+  assert dfs_n_queens(5) == [[0, 2, 4, 1, 3], [0, 3, 1, 4, 2], [1, 3, 0, 2, 4], [1, 4, 2, 0, 3], [2, 0, 3, 1, 4], [2, 4, 1, 3, 0], [3, 0, 2, 4, 1], [3, 1, 4, 2, 0], [4, 1, 3, 0, 2], [4, 2, 0, 3, 1]]
+`) })
+```
+
+`dfs_n_queens(5)` should return `[[0, 2, 4, 1, 3], [0, 3, 1, 4, 2], [1, 3, 0, 2, 4], [1, 4, 2, 0, 3], [2, 0, 3, 1, 4], [2, 4, 1, 3, 0], [3, 0, 2, 4, 1], [3, 1, 4, 2, 0], [4, 1, 3, 0, 2], [4, 2, 0, 3, 1]]`.
+
+```js
+({ test: () => runPython(`
+  assert dfs_n_queens(5) == [[0, 2, 4, 1, 3], [0, 3, 1, 4, 2], [1, 3, 0, 2, 4], [1, 4, 2, 0, 3], [2, 0, 3, 1, 4], [2, 4, 1, 3, 0], [3, 0, 2, 4, 1], [3, 1, 4, 2, 0], [4, 1, 3, 0, 2], [4, 2, 0, 3, 1]]
+  assert dfs_n_queens(3) == []
+`) })
+```
+
+`len(dfs_n_queens(5))` should be `10`.
+
+```js
+({ test: () => runPython(`
+  assert len(dfs_n_queens(5)) == 10
+  assert len(dfs_n_queens(6)) == 4
+`) })
+```
+
+`len(dfs_n_queens(8))` should be `92`.
+
+```js
+({ test: () => runPython(`
+  assert len(dfs_n_queens(8)) == 92
+  assert len(dfs_n_queens(5)) == 10
+
+`) })
+```
+
+# --seed--
+
+## --seed-contents--
+
+```py
+
+```
+
+# --solutions--
+
+```py
+def dfs_n_queens(n):
+    if n < 1:
+        return []
+
+    results = []
+
+    def is_safe(queens, row, col):
+        for r, c in enumerate(queens):
+            if c == col or abs(row - r) == abs(col - c):
+                return False
+        return True
+
+    def dfs(queens):
+        row = len(queens)
+        if row == n:
+            results.append(queens[:])
+            return
+        for col in range(n):
+            if is_safe(queens, row, col):
+                queens.append(col)
+                dfs(queens)
+                queens.pop()
+
+    dfs([])
+    return results
+```

curriculum/structure/blocks/lab-n-queens-problem.json

@@ -0,0 +1,15 @@
+{
+  "name": "Implement the N-Queens Algorithm",
+  "isUpcomingChange": true,
+  "dashedName": "lab-n-queens-problem",
+  "helpCategory": "Python",
+  "blockLayout": "link",
+  "challengeOrder": [
+    {
+      "id": "68dbc6b7e8f794a2ae69bc74",
+      "title": "Implement the N-Queens Algorithm"
+    }
+  ],
+  "blockType": "lab",
+  "usesMultifileEditor": true
+}

curriculum/structure/superblocks/full-stack-developer.json

@@ -775,6 +775,7 @@
             "lab-adjacency-list-to-matrix-converter",
             "workshop-breadth-first-search",
             "lab-depth-first-search",
+            "lab-n-queens-problem",
             "review-graphs-and-trees",
             "quiz-graphs-and-trees"
           ]