[Superposition] Add workbook solutions for tasks 13-17 (#282)

Co-authored-by: Scott Carda <55811729+ScottCarda-MS@users.noreply.github.com>
Co-authored-by: Mariia Mykhailova <mamykhai@microsoft.com>

Author: 3 people

Superposition/ReferenceImplementation.qs

@@ -307,16 +307,14 @@ namespace Quantum.Kata.Superposition {
     //
     // Goal: create an equal superposition of the four basis states given by the bit strings.
     operation FourBitstringSuperposition_Reference (qs : Qubit[], bits : Bool[][]) : Unit is Adj {
-        let N = Length(qs);
-
         using (anc = Qubit[2]) {
             // Put two ancillas into equal superposition of 2-qubit basis states
             ApplyToEachA(H, anc);
 
             // Set up the right pattern on the main qubits with control on ancillas
             for (i in 0 .. 3) {
-                for (j in 0 .. N - 1) {
-                    if ((bits[i])[j]) {
+                for (j in 0 .. Length(qs) - 1) {
+                    if (bits[i][j]) {
                         (ControlledOnInt(i, X))(anc, qs[j]);
                     }
                 }

Superposition/Superposition.ipynb

@@ -470,7 +470,14 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "### Task 12*. Hardy state.\n",
+    "*Can't come up with a solution? See the explained solution in the [Superposition Workbook](./Workbook_Superposition_Part2.ipynb#threestates-twoqubits).*"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "### <a name=\"hardy-state\"></a>Task 12*. Hardy state.\n",
     "\n",
     "**Input:** Two qubits in the $|00\\rangle$ state.\n",
     "\n",
@@ -500,7 +507,14 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "### Task 13. Superposition of $|0 \\dots 0\\rangle$ and the given bit string.\n",
+    "*Can't come up with a solution? See the explained solution in the [Superposition Workbook](./Workbook_Superposition_Part2.ipynb#hardy-state).*"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "### <a name=\"superposition-of-zero-and-given-bit-string\"></a>Task 13. Superposition of $|0 \\dots 0\\rangle$ and the given bit string.\n",
     "\n",
     "**Inputs:** \n",
     "\n",
@@ -529,7 +543,14 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "### Task 14. Superposition of two bit strings.\n",
+    "*Can't come up with a solution? See the explained solution in the [Superposition Workbook](./Workbook_Superposition_Part2.ipynb#superposition-of-zero-and-given-bit-string).*"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "### <a name=\"superposition-of-two-bit-strings\"></a>Task 14. Superposition of two bit strings.\n",
     "\n",
     "**Inputs:** \n",
     "\n",
@@ -560,12 +581,19 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "### Task 15*. Superposition of four bit strings.\n",
+    "*Can't come up with a solution? See the explained solution in the [Superposition Workbook](./Workbook_Superposition_Part2.ipynb#superposition-of-two-bit-strings).*"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "### <a name=\"superposition-of-four-bit-strings\"></a>Task 15*. Superposition of four bit strings.\n",
     "\n",
     "**Inputs:** \n",
     "\n",
     "1. $N$ ($N \\ge 1$) qubits in the $|0 \\dots 0\\rangle$ state.\n",
-    "2. Four bit strings of length $N$, represented as `Bool[][]` `bits`. `bits` is an $4 \\times N$ which describes the bit strings as follows: `bits[i]` describes the `i`-th bit string and has $N$ elements. You are guaranteed that all four bit strings will be distinct.\n",
+    "2. Four bit strings of length $N$, represented as `Bool[][]` `bits`. `bits` is an $4 \\times N$ array which describes the bit strings as follows: `bits[i]` describes the `i`-th bit string and has $N$ elements. You are guaranteed that all four bit strings will be distinct.\n",
     "\n",
     "**Goal:**  Change the state of the qubits to an equal superposition of the four basis states given by the bit strings.\n",
     "\n",
@@ -595,7 +623,14 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "### Task 16**. W state on $2^k$ qubits.\n",
+    "*Can't come up with a solution? See the explained solution in the [Superposition Workbook](./Workbook_Superposition_Part2.ipynb#superposition-of-four-bit-strings).*"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "### <a name=\"wstate-on-2k-qubits\"></a>Task 16**. W state on $2^k$ qubits.\n",
     "\n",
     "**Input:** $N = 2^k$ qubits in the $|0 \\dots 0\\rangle$ state.\n",
     "\n",
@@ -627,7 +662,14 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "### Task 17**. W state on an arbitrary number of qubits.\n",
+    "*Can't come up with a solution? See the explained solution in the [Superposition Workbook](./Workbook_Superposition_Part2.ipynb#wstate-on-2k-qubits).*"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "### <a name=\"wstate-on-arbitray-number-of-qubits\"></a>Task 17**. W state on an arbitrary number of qubits.\n",
     "\n",
     "**Input:** $N$ qubits in the $|0 \\dots 0\\rangle$ state ($N$ is not necessarily a power of 2).\n",
     "\n",
@@ -654,6 +696,13 @@
     "    // ...\n",
     "}"
    ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "*Can't come up with a solution? See the explained solution in the [Superposition Workbook](./Workbook_Superposition_Part2.ipynb#wstate-on-arbitray-number-of-qubits).*"
+   ]
   }
  ],
  "metadata": {
@@ -666,7 +715,7 @@
    "file_extension": ".qs",
    "mimetype": "text/x-qsharp",
    "name": "qsharp",
-   "version": "0.4"
+   "version": "0.10"
   }
  },
  "nbformat": 4,

Superposition/Tasks.qs

@@ -202,7 +202,7 @@ namespace Quantum.Kata.Superposition {
     // Inputs:
     //      1) N qubits in |0...0⟩ state
     //      2) four bit string represented as Bool[][] bits
-    //         bits is an array of size 4 x N which describes the bit strings as follows:
+    //         bits is an array of size 4 x N array which describes the bit strings as follows:
     //         bits[i] describes the i-th bit string and has N elements.
     //         All four bit strings will be distinct.
     //