combinotorics

Consider a n*n chessboard. A person moves along the lines of the chessboard such that the sum in the y axis is greater than or equal to the sum in the x axis. Find the number of ways of going from one corner to the other corner.

7 Answers

21
Arnab Kundu ·

What do you mean by Sum?

1
aritraa dfdf ·

by sum i mean the total distance already covrered

1
Md. Shahbaz Siddiqi ·

is answer n2(n+1)/2

11
Shaswata Roy ·

Is it (2n)!n!2

7
Sigma ·

@Shaswata: ur ans wud hav been correct if the q wud hav been: In how many shortest possible ways can 1 reach the diagonal opp sides of the chessboard??

21
Shubhodip ·

This is Catalan numbers.

The answer is C_{n-1}

Just look at the permutation matrix and you are done. (Basically a bijection)

I don't have time to explain sorry

11
sougata nag ·

let the no be g.
then 2g=Σ1→n2rCr+Σ1≤i,j≤ni+jCi

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