Is it rated?)

Is it a hiring contest?

Wow, that sounds amazing! Sadly I have 3 exams in the 3 days of the contests, but I will probably participate in the warm-up round. Btw, what level of knowledge is required about quantum computing in order to participate? also, if the practice and contests rounds will be available after the contest ends for people who failed to participates on time it would be great :D

I have heard of Q# about 2 months ago but haven't try it. I will give it a shot this time.

stupid language, useless. this is a waste of my time. codeforce should give more brainf*ck language contests. because codeforces’ retardness is f*cking my brain. stupid codeforces. stupid contestants

Excited to code Q#. Are the problems typical problem-solving style or some kind of different one? Like, using unitary matrix or something.-

Is quantum computing background required for this contest?

I had a doubt. Will I be able to test my code on the custom invocation like code of any other language? Please pardon if you do not find this comment sensible enough.

Can I do this contest without using any Mrkvosoft tools?

:^)

Will system tests be handled by quantum computers? :D

Is there any materials about Quantum Programming?

I'm very interested in this but having no idea how to learn about it.

Interested in this contest but won't participate for my poor knowledge of quantum mechanics and unfamiliarity with Q# and even C#.

I'm interested in Q#, and looking forward to this contest!

Can only use Q#? 这次比赛只能用Q#吗 Google Translate....Chinese->English.....

Is there any guide to the quantum algorithms for Complete Idiots (tm)?

may i use any other language other than Q#

Expected ranklist:

1. tourist

... Remaining ones are difficult to decide.

Oops, why doesn't the following work for G?

    operation Solve (x : Qubit[], y : Qubit, k : Int) : ()
    {
        body
        {
            Set(Zero,y);
            CNOT(x[k],y);
        }
    }

How can I find that "Tutorial blogpost", where the specification of an Oracle is given?

It seems the checker does not recognize compilation errors. Sent non-compilable code and got WA.

Guys I would like to ask a question.

Since this is a practice contest, I think its ethical to take help.

However, I would still ask you guys, should I ask a question related to the contest ?

Why no online IDE for this?

The linked one isn't working properly.

I want to test my Q# method but I don't really know how. I understand that I can make a C# driver class (since I'm using Visual Studio Code, that is done for me), but I can't call the Q# method because it takes a Qubit[], which in C# seems to be a QArray(). Now, normally, this would be no problem, and I would just look up the documentation for QArray and Qubit to see how to create them, but I can't find documentation for these two classes anywhere. I suppose I am just bad at looking, any help would be appreciated.

Nickolas, One question please. Are the inputs of Problem G any random state of qubits? Like, x[k] = α|0 >  + β|1 >  with any proper α and β?

Is there a Q# issue-tracker somewhere? Some of the error-messages are not very helpful and look like a bug in the compiler:

• error QS0001: Internal error: The index was outside the range of elements in the list. occurs if the body of an operation with a return value contains only comments. (Just an empty body does produce a proper error message.)
• error QS0001: Internal error: Parsing produced an error node without logging an error occurs really often for me, mostly when I guess the syntax wrongly. Some examples of such wrong syntax are: & as bitwise operator, ! or ~ as boolean not, braced-initializer for a new array, a single-statement for-loop without {}, a single-statement else without {}.
• error QS0001: Internal error: ("C:\\<path-to-folder>\\prog.qs", Ln: 112, Col: 2): The combinator 'many' was applied to a parser that succeeds without consuming input and without changing the parser state in any other way. (If no exception had been raised, the combinator likely would have entered an infinite loop.) occurs if your create imbalanced curly brackets by commenting some }. Surprisingly, deleting them instead of commenting produced a different (more reasonable) error.

I also encountered a strange crash that is quite sensitive to code changes (The crash does not occur on TIO.):

using System;
using Microsoft.Quantum.Simulation.Simulators;
namespace Solution
{
	public class Driver
	{
		public static void Main(string[] args)
		{
			using (var sim = new QuantumSimulator())
			{
				string res = MMain.Run(sim).Result;
				System.Console.WriteLine($"Did: | {res}");
			}
			System.Console.WriteLine("Done.");
		}
	}
}

namespace Solution {
    open Microsoft.Quantum.Primitive;
	open Microsoft.Quantum.Extensions.Diagnostics;

	operation F() :(){
		body {
			using (q = Qubit[2]) {
			using (A = Qubit[1]) {
				X(q[0]);
				H(q[0]);
				CNOT(q[0], q[1]);
				DumpMachine("");
				
				ResetAll(q);
			}
			}
		}
	}
	operation MMain() : String {
		body {
			F();
			F();
			
			mutable mess = "";
			return mess;
		}
	}
}

It looks like the unused qbit A got flipped.

Edit: I just figured out how to dump to console ('DumpMachine("")'):

Ids:    [2;1;0;]
Wavefunction:
0:      0.707107        0
1:      0       0
2:      0       0
3:      -0.707107       0
4:      0       0
5:      0       0
6:      0       0
7:      0       0
Ids:    [2;1;0;]
Wavefunction:
0:      0.707107        0
1:      0       0
2:      0       0
3:      0       0
4:      -0.707107       0
5:      0       0
6:      0       0
7:      0       0

Unhandled Exception: System.AggregateException: One or more errors occurred. (Released qubits are not in zero state.) ---> Microsoft.Quantum.Simulation.Simulators.Exceptions.ReleasedQubitsAreNotInZeroState: Released qubits are not in zero state.
   at Microsoft.Quantum.Simulation.Simulators.QuantumSimulator.QSimQubitManager.ReleaseOneQubit(Qubit qubit, Boolean usedOnlyForBorrowing)
   at Microsoft.Quantum.Simulation.Common.QubitManager.Release(QArray`1 qubitsToRelease)
...

Something's seriously wrong on my machine xD.

I have a question.

let's say q[0] is in state |0> + |1>. I use the operation CNOT(q[0],q[1]) so I have |00>+|11>. Now measure res=M(q[0]). Now if I do res2=M(q[1]) will I always get the exact same measurement or different. i.e does measuring q[0] collapse q[1] or will q[1] still remain in superposition.

The document says:

The qubits should be in the computational Zero state at the end of the statement block; simulators are encouraged to enforce this.

Is it enforced in the judger of this contest? I got WA in Problem I if I don't reset them, and got AC if I do. I wonder whether this means I produced a wrong answer or the judger was unhappy because I didn't reset.

Fastest Editorial ever!!! It comes out (partially) 2 days before contest even ends O:

Any hidden tricks for Deutsch Josza? I don't know what am I doing wrong.

    operation Solve (N : Int, Uf : ((Qubit[], Qubit) => ())) : Bool
    {
        body
        {
			mutable res = true;
			using(q1 = Qubit[1])
			{
				Set(One, q1[0]);
				H(q1[0]);
				using(qs = Qubit[N])
				{
					// generate input space
					for(i in 1..N)
					{
						H(qs[i-1]);
					}
					Uf((qs, q1[0]));
					// applying Hadamard again
					for(i in 1..N)
					{
						H(qs[i-1]);
					}
					for(i in 1..N)
					{
						if(M(qs[i-1]) == One )
						{
							set res = false;
						}
				
					}
				}
			}
			return res;
        }
    }

completely new to this topic

learn quantum computing in 6 days

wow

Hey would it be possible to include a driver program so that we could test our code in the actual contest? I'm having trouble in using online IDE link given.

Will the actual contest have tougher problems? otherwise it would become a time race.

Is there any difference between the functions ResultAsInt and PositiveIntFromResultArr?

I am worried that the judge does not working because it always returned AC for every problem. Can someone confirm it is possible to get WA ?

i have no object oriented programming knowledge.I have been using only functional(haskell) and procedural languages(C,C++).Will Q# suit me in this case.If not is their any alternative?

PS even though c++ has oops i have never tried or used it.

Is it ok that smart tabs do not work at all in Q# sources in Visual Studio 2017?

Basically, whenever I press Enter to create a new line, a new line is created, but it's empty and does not contain any indentation:

        body
        {
<<< cursor is now there
        }

I've already went to Tools -> Options -> Text Editor -> All Languages -> Tabs and switched "Indenting" to "Smart", but it didn't help with Q# source files. Indentation in C# works as expected.

Is there any analogue of AssertQubitState, but for n-qubit states? I was able to find AssertProbInt, but it checks probabilities only and does not check phase shifts. Basically, I want to write a unit-test for problem B.

Thanks, that was very educational — I've read about quantum computing before and had a very basic understanding that the state vector could be evolved through unitary matrices and measurement, but actually coding it help understanding a lot, particularly that it's non-trivial to construct the unitary matrices from gates.

I'm feeling pretty happy that I managed to derive Deutsch-Jozsa for N=1 before reading the Wikipedia page. It's still hurting my brain that even though the oracle doesn't modify any of the input qubits, the algorithm throws away the output and just manipulates the inputs.

Can someone explain C to me?

Are tests running? It seems like all submissions are in queue but none is being evaluated

I realized that the pdf with problem explanations has some issues with copying the code which makes it fail compilation. I'll be fixing it in the following editorials. Meanwhile, here is the code from the pdf that you can copy and run.

namespace Solution {
    open Microsoft.Quantum.Primitive;
    open Microsoft.Quantum.Canon;
    operation Solve (q : Qubit, sign : Int) : ()
    {
        body
        {
            if (sign == -1) {
                X(q);
            }
            H(q);
        }
    }
}

namespace Solution {
    open Microsoft.Quantum.Primitive;
    open Microsoft.Quantum.Canon;

    operation Solve (q : Qubit) : Int
    {
        body
        {
            if (Measure([PauliX], [q]) == Zero) {
                return 1;
            }
            return -1;
        }
    }
}

namespace Solution {
    open Microsoft.Quantum.Primitive;
    open Microsoft.Quantum.Canon;

    operation Solve (x : Qubit[], y : Qubit, k : Int) : ()
    {
        body
        {
            CNOT(x[k], y);
        }
    }
}

What's wrong in this code for problem H?? I'm getting WA.

using(q1 = Qubit[1])
        {
            if(counter == 1)
            {
                Set(One, q1[0]);
            }
            else
            {
                Set(Zero, q1[0]);
            }
            CNOT(q1[0],y);
            Set(Zero,q1[0]);
        }          
    }

Thanks in Advance!!

operation Solve (qs : Qubit[]) : () { body { let n = Length(qs); for (index in 1 ..n) { X( qs[index]); } } }

http://mirror.codeforces.com/contest/1001/submission/39862662 ( the last index is out of bound)

why it's WRONG ANSWER instead of RUNTIME ERROR

This is my code for the H question. It seems to work for all sorts of superpositions as well, but I got a wrong answer. Is there an issue with using an extra qubit and discarding it, as I did below?

namespace Solution {
    open Microsoft.Quantum.Primitive;
    open Microsoft.Quantum.Canon;

    operation Solve (x : Qubit[], y : Qubit) : ()
    {
        body
        {
            using (output = Qubit[1]){
                for (index in 0..Length(x)-1){
                        CNOT(x[index], output[0]);
                }
                
                CNOT(output[0], y);
            }
        }
    }
}

I need help with this part of I problem: Uf : ((Qubit[], Qubit) => ())

How should this array be represented. If I wanted to, let's say CNOT first and second element, what should I write? CNOT(Uf.Qubit[0],Uf.Qubit[1])?

What about syntax highlighting plugins for other editors than VS? If I want to use, say, Sublime Text or Vim (and compile with .NET SDK or by submitting), is there a way to get correct syntax highlighting? C# syntax isn't the same.

In problem G, is y guaranteed to be initialised to ?

I wanted to set it to by first measuring it, which puts it in one of the Pauli Z basis states, and then flipping it if the measured eigenvalue was  - 1. It gave WA.

I'm aware entanglement means I shouldn't measure in oracles, but if y is entangled with something (not ), then I'm not going to set its value to x_k using just CNOT anyway.

The warmup round is over! Here are the editorials for the tasks.

Can someone write me I problem, so I can examine it. I have hard time dealing with compilation errors..