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Le Monde puzzle [#887bis]

November 16, 2014

As mentioned in the previous post, an alternative consists in finding the permutation of {1,…,N} by “adding” squares left and right until the permutation is complete or no solution is available. While this sounds like the dual of the initial solution, it brings a considerable improvement in computing time, as shown below. I thus redefined […]

Le Monde puzzle [#887]

November 15, 2014

A simple combinatorics Le Monde mathematical puzzle: N is a golden number if the sequence {1,2,…,N} can be reordered so that the sum of any consecutive pair is a perfect square. What are the golden numbers between 1 and 25? Indeed, from an R programming point of view, all I have to do is to […]

Le Monde puzzle [#882]

October 14, 2014

A terrific Le Monde mathematical puzzle: All integers between 1 and n² are written in an (n,n)  matrix under the constraint that two consecutive integers are adjacent (i.e. 15 and 13 are two of the four neighbours of 14). What is the maximal value for the sum of the diagonal of this matrix? Indeed, when considering […]

Le Monde puzzle [#879]

September 21, 2014

Here is the last week puzzle posted in Le Monde: Given an alphabet with 26 symbols, is it possible to create 27 different three-symbol words such that all symbols within a word are different all triplets of symbols are different there is no pair of words with a single common symbol Since there are 28x27x26/3×2=2925 […]

Le Monde puzzle [#875]

July 12, 2014

I learned something in R today thanks to Le Monde mathematical puzzle: A two-player game consists in A picking a number n between 1 and 10 and B and A successively choosing and applying one of three transforms to the current value of n n=n+1, n=3n, n=4n, starting with B, until n is larger than […]


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