Permutations

Traditional Problems Lexicographic Ordering Problems

Straight to the problem, if n = 3 and m = 5 then the lexicographic order of the combination is :

1 2 3 = 1
1 2 4 = 2
1 2 5 = 3
1 3 4 = 4 
1 3 5 = 5
1 4 5 = 6
2 3 4 = 7
2 3 5 = 8
2 4 5 = 9
3 4 5 = 10

Input and Output

• Given the index, print the assocating combination
  The input will look something like :
  1 n m k
  

• Given the combination, print the associating index
  The input will look something like :
  2 n m k1 k2 ... kn
  

Solution (Yogy Namara) :

10--6--3--1 | | 1 | | 1 | 2--1 | | 1 | 1--1 3--2--1 | | 1 | 1--1 1--1--1

Pascal triangle 1 1 1 1 2 1 1 3 3 1 1 4 6 4 1 1 5 10 10 5 1

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