红宝石 |数组排列（）函数

Array#permutation() : permutation()是一个 Array 类方法，它返回数组元素长度为 n 的所有排列，然后返回数组本身。

Syntax: Array.permutation()

Parameter: Array

Return: all permutations of length n of the elements of the array, then return the array itself.

示例 #1：

# Ruby code for permutation() method
  
# declaring array
a = [18, 22, 33, nil, 5, 6]
  
# declaring array
b = [1, 4, 1, 1, 88, 9]
  
# declaring array
c = []
  
# permutation method example
puts "permutation() method form : #{a.permutation(2).to_a}\n\n"
  
puts "permutation() method form : #{b.permutation(1).to_a}\n\n"
  
puts "permutation() method form : #{c.permutation(4).to_a}\n\n"

输出 ：

permutation() method form : [[18, 22], [18, 33], [18, nil], [18, 5], [18, 6], [22, 18], [22, 33], [22, nil], [22, 5], [22, 6], [33, 18], [33, 22], [33, nil], [33, 5], [33, 6], [nil, 18], [nil, 22], [nil, 33], [nil, 5], [nil, 6], [5, 18], [5, 22], [5, 33], [5, nil], [5, 6], [6, 18], [6, 22], [6, 33], [6, nil], [6, 5]]

permutation() method form : [[1], [4], [1], [1], [88], [9]]

permutation() method form : []

示例 #2：

# Ruby code for permutation() method
  
# declaring array
a = ["abc", "nil", "dog"]
  
# declaring array
c = [nil]
  
# declaring array
b = ["cow", nil, "dog"]
  
# permutation method example
puts "permutation() method form : #{a.permutation(2).to_a}\n\n"
  
puts "permutation() method form : #{b.permutation(1).to_a}\n\n"
  
puts "permutation() method form : #{c.permutation(4).to_a}\n\n"

输出 ：

permutation() method form : [["abc", "nil"], ["abc", "dog"], ["nil", "abc"], ["nil", "dog"], ["dog", "abc"], ["dog", "nil"]]

permutation() method form : [["cow"], [nil], ["dog"]]

permutation() method form : []