feat(2023): add solution for challenge #16

2023/challenge-16/README.md

@@ -0,0 +1,51 @@
+# Challenge #16: Friday deployment
+
+Yesterday, someone did a production deployment and the application for assembling Christmas trees broke. We've been asked to fix it as soon as possible.
+
+The problem is that the format of the trees has changed. **It's an array of numbers… but it should be an object!** For example, the tree: `[3, 1, 0, 8, 12, null, 1]` looks like this:
+
+```js
+//        3
+//      /   \
+//     1     0
+//    / \     \
+//   8  12     1
+```
+
+What we need is to transform the array into an object where each node of the tree has `value`, `left`, and `right` properties.
+
+For example, running your `transformTree` function with `[3, 1, 0, 8, 12, null, 1]` should return this:
+
+```js
+{
+  value: 3,
+  left: {
+    value: 1,
+    left: {
+      value: 8,
+      left: null,
+      right: null
+    },
+    right: {
+      value: 12,
+      left: null,
+      right: null
+    }
+  },
+  right: {
+    value: 0,
+    left: null,
+    right: {
+      value: 1,
+      left: null,
+      right: null
+    }
+  }
+}
+```
+
+The elf on duty who tried to solve the problem before going home, left us some clues:
+
+- **If a node doesn't have a value, it's represented with null. Therefore, if a node has a null value, it won't have any children.**
+- **The root node is at index 0 in the array.**
+- **There's a relationship between the index of a node and the index of its children. Look for the pattern!**

2023/challenge-16/challenge-16.test.ts

@@ -0,0 +1,176 @@
+import { describe } from 'vitest'
+import { transformTree } from './challenge-16'
+
+const TEST_CASES: TestCases<
+  Array<number | null>,
+  Record<string, any> | null
+> = [
+  { args: [], expected: null },
+  {
+    args: [1],
+    expected: {
+      value: 1,
+      left: null,
+      right: null,
+    },
+  },
+  {
+    args: [1, 2, 3],
+    expected: {
+      value: 1,
+      left: {
+        value: 2,
+        left: null,
+        right: null,
+      },
+      right: {
+        value: 3,
+        left: null,
+        right: null,
+      },
+    },
+  },
+  {
+    args: [1, 2, 3, 4, 5],
+    expected: {
+      value: 1,
+      left: {
+        value: 2,
+        left: {
+          value: 4,
+          left: null,
+          right: null,
+        },
+        right: {
+          value: 5,
+          left: null,
+          right: null,
+        },
+      },
+      right: {
+        value: 3,
+        left: null,
+        right: null,
+      },
+    },
+  },
+  {
+    args: [1, 2, 3, 4, 5, 6, 7],
+    expected: {
+      value: 1,
+      left: {
+        value: 2,
+        left: {
+          value: 4,
+          left: null,
+          right: null,
+        },
+        right: {
+          value: 5,
+          left: null,
+          right: null,
+        },
+      },
+      right: {
+        value: 3,
+        left: {
+          value: 6,
+          left: null,
+          right: null,
+        },
+        right: {
+          value: 7,
+          left: null,
+          right: null,
+        },
+      },
+    },
+  },
+  {
+    args: [17, 0, null, null, 1],
+    expected: {
+      value: 17,
+      left: {
+        value: 0,
+        left: null,
+        right: {
+          value: 1,
+          left: null,
+          right: null,
+        },
+      },
+      right: null,
+    },
+  },
+  {
+    args: [3, 1, 0, 8, 12, null, 1],
+    expected: {
+      value: 3,
+      left: {
+        value: 1,
+        left: {
+          value: 8,
+          left: null,
+          right: null,
+        },
+        right: {
+          value: 12,
+          left: null,
+          right: null,
+        },
+      },
+      right: {
+        value: 0,
+        left: null,
+        right: {
+          value: 1,
+          left: null,
+          right: null,
+        },
+      },
+    },
+  },
+  {
+    args: [2, 7, 5, null, 6, null, 9, null, null, 1, 11, null, null, null, 10],
+    expected: {
+      value: 2,
+      left: {
+        value: 7,
+        left: null,
+        right: {
+          value: 6,
+          left: {
+            value: 1,
+            left: null,
+            right: null,
+          },
+          right: {
+            value: 11,
+            left: null,
+            right: null,
+          },
+        },
+      },
+      right: {
+        value: 5,
+        left: null,
+        right: {
+          value: 9,
+          left: null,
+          right: {
+            value: 10,
+            left: null,
+            right: null,
+          },
+        },
+      },
+    },
+  },
+]
+
+describe('Challenge #16: Friday deployment', () => {
+  buildChallengeTestCases({
+    cases: TEST_CASES,
+    fn: transformTree,
+  })
+})

2023/challenge-16/challenge-16.ts

@@ -0,0 +1,38 @@
+export function transformTree(tree: Array<number | null>) {
+  if (!tree.length) return null
+
+  const rootTree: Array<Record<string, any> | null> = [
+    {
+      value: tree[0],
+      left: null,
+      right: null,
+    },
+  ]
+
+  let index = 1
+
+  for (const node of tree.slice(1)) {
+    let subTree = null
+
+    if (node != null) {
+      const parentIndex = index - Math.trunc(index / 2) - 1
+      const side = index % 2 === 0 ? 'right' : 'left'
+      const parent = rootTree[parentIndex]
+
+      subTree = {
+        value: node,
+        left: null,
+        right: null,
+      }
+
+      if (parent) {
+        parent[side] = subTree
+      }
+    }
+
+    index++
+    rootTree.push(subTree)
+  }
+
+  return rootTree[0]
+}

README.md

@@ -104,7 +104,7 @@ This repository contains the solutions to the challenges proposed by [@midudev](
 | 13  |      Calculating the time      |       🟢       | [Show](https://adventjs.dev/challenges/2023/13) | [Go](./2023/challenge-13/challenge-13.ts) |
 | 14  |        Avoid the alarm         |       🟠       | [Show](https://adventjs.dev/challenges/2023/14) | [Go](./2023/challenge-14/challenge-14.ts) |
 | 15  |        Autonomous robot        |       🟠       | [Show](https://adventjs.dev/challenges/2023/15) | [Go](./2023/challenge-15/challenge-15.ts) |
-| 16  |               --               |       --       |                       --                        |                    --                     |
+| 16  |       Friday deployment        |       🟢       | [Show](https://adventjs.dev/challenges/2023/16) | [Go](./2023/challenge-16/challenge-16.ts) |
 | 17  |               --               |       --       |                       --                        |                    --                     |
 | 18  |               --               |       --       |                       --                        |                    --                     |
 | 19  |               --               |       --       |                       --                        |                    --                     |