January 2026: Timely Journey

What a great way to kick off the new year with possibly my favourite Jane Street puzzle so far! With nothing but a mysterious image to go off, this was a classic case for collaboration between me and Fred Vu.

Stats:

Difficulty: 9/10

Enjoyability: 9/10

Leaderboard Placing: 1/52

The first thing one notices is that the crossword-like grid has 12 across clues and 12 down clues, each of which has one red square and one blue square (with no coloured squares shared between clues). This matches the strings of digits towards the bottom-left and top-right of the page: there are 12 rows of digits at bottom-left and 12 columns of digits at top-right, each of which has one digit coloured red and one digit coloured blue (with the exception of one column, which has two blue digits). This leads one to believe that each row of digits corresponds to an across clue, and each column of digits corresponds to a down clue, but one is left with the challenging task of figuring out what the numbers mean, and which strings of digits correspond to which clues in the grid.

The first key step in interpreting the numbers came from Fred, who realised that many of the digit strings are plausible coordinates in the degrees/minutes/seconds format. This was partially inspired by the globe which can be seen on the left-hand side of the image, as well as the red and blue pins sitting in the nearby dish, leading us to believe that we might have to “pin” certain locations on a world map. The title of the puzzle, “Timely Journey”, hinted that these locations may correspond to different time zones, and that as one went through the list of clues, one would complete a “journey” around the globe, passing through each time zone. This “Timely Journey” would be reminiscent of how different parts of the world successively enter the new year, and since this puzzle was released on New Year’s Day, we were fairly confident we were on the right track with this line of thinking. Our first major confirmation of this was our discovery, after some digging, that the latitude of Cairo, Egypt (as listed on Wikipedia) is 30°02′40″N, which perfectly matches the second across clue, whereas the longitude of Algiers, Algeria (as listed on Wikiedia) is 3°05′14″E, which very closely matches the first down clue. This led to the hypothesis, bolstered by the partially showing caps lock on the keyboard, that each across clue gave the latitude of a world capital, whereas each down clue gave the longitude of a world capital. However, we were still unsure, as there were many clues we couldn’t match to a city, and those that we could were often slightly off the mark.

We bumbled around for a while trying to match clues to cities — never quite sure if we were interpreting the puzzle correctly — until I made an observation that cemented our confidence that we were on the right track: if you read the first two or three digits of the longitudinal clues from left to right, they seem to increase up to approximately 180, before they decrease again. In particular, from left to right we have 30, 36, 60, 100, 140, 155, 169, 134, 113, 79, 56, 25. This strongly suggests either an east-west or west-east journey across the globe, with longitudes flipping from east to west (or vice versa) once they cross the date line at 180°. This gave us the confidence to double our search efforts, and before long we’d found some more capital cities which very closely matched some of the coordinates given, namely Baku, Azerbaijan, and Bishkek, Kyrgyzstan, whose latitudes of 40°22′32″N and 42°52′29″N (as given on Wikipedia) closely matched the third and fourth across clues respectively, and Nairobi, Kenya, whose longitude of 36°49′02″E (as given on Wikipedia) closely matched the second down clue. This was enough to not only confirm that we were doing the right thing, but also to establish the correspondence between coordinates and locations in the crossword puzzle — for there’s only one across clue in the grid with five letters, meaning Cairo had to go there, and only one across clue in the grid with four letters, meaning Baku had to go there. We noticed that Algiers and Nairobi would then slot perfectly in with these answers, meaning we traverse the crossword puzzle counterclockwise as we go down the list of latitudinal clues and across the list of longitudinal clues, whilst traversing the Earth in time zones from west to east. This significantly simplified the search from that point on, since we always knew the number of letters in the city we were searching for, and as we continued to fill out the grid, we sometimes knew what some of those letters had to be.

There were only two complications remaining. The first was determining how to interpret digit clues of differing lengths, and the second was the fact that many clues couldn’t be matched to a city, particularly those whose longitudes corresponded to the middle of the Pacific Ocean. The first problem was dispatched of relatively easily: it seemed from what we’d already solved that the last two digits always gave seconds, while the next two digits to the left gave minutes, and however many digits remained at the front gave degrees. The second problem was harder to solve, but we did so by realising we had to relax the kinds of locations we were looking for. We discovered relatively early that we weren’t necessarily looking for capital cities, with Fred’s realisation that Yekaterinburg, Russia solved one of the longitudinal clues, and my realisation that Guayaquil, Ecuador solved another. So, for a while we thought we were simply looking for major cities, but then the Pacific Ocean was still a stumbling block. The breakthrough was my realisation that the island of Martinique solved one of the latitudinal clues, plus fit into the parts of the crossword we’d already solved; from there, we relaxed our search to essentially any “location” that matched the coordinates, and it wasn’t long before we had the entire crossword grid filled out.

It didn’t take us long to extract the answer to the puzzle from here on out. Following a hunch, I started traversing the completed crossword counterclockwise, each time taking the letter from the blue square and shifting it forward through the alphabet according to the blue digits from the corresponding clue (I didn’t realise it at the time, but this was perhaps hinted at by the “shift” key being visible in the puzzle photo). Note that the longitudinal clue with the two blue digits 1 and 0 indicates a forward shift of 10 units. After traversing the entire crossword puzzle, we obtained the message “WHAT RED LETTERS ARE MISSING?” Fred applied the same process to the red squares in the crossword puzzle, finding that they sequentially spelled out the alphabet. There being only 24 red squares, two letters were missing, and those were “T” and “Z”, which gave us our final answer of “TZ”. Given that time and time zones were a strong theme throughout the puzzle, we knew we’d found the right answer.

Note that we didn’t use all of the information included in the original photo. We thought most of it was noise, but it turns out that the scrabble tiles and dominoes hinted at a past Jane Street puzzle which used similar ideas, and the plant, pentomino, and dice at the top of the photo hinted at the time zones theme. It’s somewhat amusing that we solved the puzzle without all these hints; Fred definitely did well to recognise the numbers as coordinates without any extra info.

Solving this puzzle from start to finish was such a satisfying process, and as always, the collaboration with Fred was both highly fun and synergistic. We hope to see more puzzles like this throughout 2026!