n=4 and k=3 . team name can be formed by four digits 1,2,3,4 . so n=4 now make team number using any three digits so that b1numbers which are in form b1
【在 d******e 的大作中提到】 : n=4 and k=3 . team name can be formed by four digits 1,2,3,4 . so n=4 now : make team number using any three digits so that b1: numbers which are in form b1
thanks for the link n choose k, 2 possibilities largest element is n: n-1 choose k-1 otherwise: n-1 choose k base case 1: m choose 0, empty base case 2: m choose m, 1