Logic Masters Deutschland e.V.

NORMAL SUDOKU rules apply. There are 5 COLORED LETTERS: C-O-V-I-D. The sum of the cells in each letter is 19. There are 4 KILLER CAGES, all sum up to 19 and ALL CONTAIN A DIFFERENT SET OF NUMBERS. A number can appear in multiple cages, but one set can only appear once (If one cage is 2-8-9, then 3-7-9 is allowed, but no other cages can contain the 2-8-9 triplet again). No number appears more than once in a cage.

There are 2 PALINDROMES: these are sequences of digits which read the same backward as forward. Every digit on these palindromes comes from a pool of 4 digits, but a palindrome not necessarily contains all 4. (In fact, one can contain exactly 3 from those 4. Let’s say the pool contains 1, 2, 3 and 4, therefore one example for the palindromes is 1-3-2-3-1 and 3-1-4-1-3).

Orthogonally adjacent cells with the sum of 5 are marked with a V, but not every possible candidate is indicated. There are 2 DIFFERENCE clues: numbers in the small circles between two cells indicate the difference between those cells. There is 1 ARROW: digits along the arrow in the grid must sum to the digit in its circle. Digits can repeat along the arrow. Digits must increase on the THERMOMETER from its bulb end. The sum of the numbers on it should stay between 35-37.

The puzzle is also available online.

LONG VERSION with a little backstory:

Let's help us to find the vaccine for COVID-19 with this SUDOKU, because obviously this is how science works. The fate of the world is in your hands. But don't worry, the brave scientists who worked on this case before, left you some clues.

First of all, NORMAL SUDOKU rules apply. You know, just the usual stuff. Each row, column, and 3x3 box contains each number from 1 to 9 exactly once. As you can see in boxes 1, 3, 5, 7 and 9 there are FIVE COLORED LETTERS: C-O-V-I-D. Yeap, that's a D, get over it. The sum of the cells in each letter is 19.

Those brave scientists have already digested the protein coat of the virus with an enzyme. It broke into four fragments, a.k.a. KILLER CAGES. All four cages sum up to 19, and all four contain a different set of numbers. A number can appear in multiple cages, but one set of three can only appear once (If one cage is 2-8-9, then 3-7-9 is totally fine, but no other cages can contain the 2-8-9 triplet again). And you know what's up with the killer cages, am I right? The sum of all numbers in a cage (marked with dashed lines) must match the small number printed in its corner. No number appears more than once in a cage.

The DNA of the virus is floating somewhere between the numbers. In order to make the antidote, we need a higher amount of it, so we have to amplify that sweet viral DNA with PCR. There is one problem though. Those silly scientists forgot the exact sequence of the nucleotide bases that form the primers, and sadly we cannot initiate PCR without primers.

However, they know that the primers contain five-five nucleotides (coded with numbers), they complement each other like the two strands of the DNA, and they are PALINDROMES, which means they are sequences of digits which read the same backward as forward (for example 4-1-7-9-7-1-4 is a palindrome, and the possible complementing sequences of it would look like this: 9-7-1-4-1-7-9 or 1-4-9-7-9-4-1 or 7-9-4-1-4-9-7).

Thank god, it is just a Sudoku, because in real life these complementing primers would be totally useless. And of course you know it from biology class, it is just a friendly reminder: there are four different nucleotide bases (A, G, C, T) in the DNA, so those primers CAN CHOOSE FROM ONLY FOUR DIFFERENT NUMBERS. Of course, it is impossible to contain all four.

The scientists also investigated the letter V from COVID, and guess what? They found two smaller V-s on it. And you know what does it mean? If there is a V between two cells, their sum must be 5! Unfortunately, they only investigated this one letter, so not every possible candidate is indicated on the grid.

They also wanted to know a little more about that D, so they studied all its cells to see if they could find any DIFFERENCE between them. And I’m sure you guessed it right: they found some! Those numbers in the small circles between two cells indicate the difference between those cells.

Although it is really pixelly, that O in box 3 is like a wheel on a road-racer: it wanted to escape all the time, so they fixed to the V with an ARROW. And I’m sure you’re familiar with the arrows, but here is a reminder: digits along an arrow in the grid must sum to the digit in its circle. Digits can repeat along the arrows.

We provided you a thermometer to check your body temperature. So THERMO SUDOKU rules also apply: digits must increase on the thermometer from its bulb end. Please, don't die or get sick during the solve, so the sum of the numbers on the thermometer should stay between 35-37 (degree Celsius, you Yankee Schwein, not Fahrenheit).