Using Javascript to calculate a random grid. Like in Sodoku the challenge was to allow only for unique numbers in each row and column hence the only duplicates occur in traveses
Example
var n = 9
[ [ 2, 3, 4, 7, 5, 9, 6, 1, 8 ],
[ 1, 2, 3, 4, 6, 5, 7, 8, 9 ],
[ 5, 1, 6, 3, 2, 4, 8, 9, 7 ],
[ 7, 8, 9, 5, 1, 2, 3, 4, 6 ],
[ 9, 5, 7, 6, 8, 3, 1, 2, 4 ],
[ 3, 7, 8, 9, 4, 1, 2, 6, 5 ],
[ 4, 6, 2, 8, 9, 7, 5, 3, 1 ],
[ 6, 9, 1, 2, 7, 8, 4, 5, 3 ],
[ 8, 4, 5, 1, 3, 6, 9, 7, 2 ] ]the most efficient one is fastGrid.js