Hello I need to solve this exercice there is 3 parts in it all related to each others

We walk in a city whose plan is organized in quadrilaterals (as are vast

sections of North American cities such as Montreal or New York). The intersections will be the

points with integer coordinates of the xy plane

The intersection (i, j) is therefore linked by streets to the

intersections (i, j 1) and (i 1, j).

We start from the intersection (0, 0) and our destination is the intersection (n, n), for n ? N

(n, n) (0, 0)(n, n)(n-1, n+1) (n-1, n+1) (n, n) (n, n) (0, 0) (0. 0)