permutation Class Reference

List of all members.

Public Member Functions
	permutation (unsigned short *y, int a, int b)
void	swap (int a, int b)
	swap the a-th and b-th digits
void	printP ()
	print the permutation
void	move_to (unsigned k)
	move to k-th permutation, destructive.

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Detailed Description

Using the method of recursion: To find the permutation of N digits in numerical order:

• When N=2: 01,10

• When N>2:

  1. Let k=2
  2. Loop through a) to c) until k is greater than N:
     1. Find the permutation of the last (N-1) digits in numerical order. (Do not alter the original permutation; just copy it in new permutation process.)

     2. Swap the k-th digit with the 1-st digit.

        _0123456789 -> 1023456789 -> 2013456789 -> ... -> 9012345678

     3. Add one to k.

  Indexing the lexicographic permutation:

  • 2!=2: "_0123456789 #1", "_0123456798 #2"
  • 3! = 6: "_0123456879 #3", "_0123456897 #4","_0123456978 #5", "_0123456987 #6"
  • ...
  • 9!=362880: ..., "_0987654321 #362880"
  • 10!=3628800: "9012345678 #362881", ..., "9876543210 #3628800"

Definition at line 38 of file 024.cpp.

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The documentation for this class was generated from the following file:

• 024.cpp