A permutation is an arrangement of selected items where order matters. Two lists can contain the same elements and still represent different arrangements when their order differs. section 26.5
Comparing lists
The lists [1, 2, 3] and [3, 1, 2] are permutations of each other because they contain the same elements in a different order. Duplicate elements count too: [1, 1, 1, 2] and [1, 2, 1, 1] match, but [1, 2, 3, 1] and [1, 2, 3] do not because one list has an extra 1. section 26.5
When solving a tile-word problem, considering every possible permutation is one possible strategy. A simpler approach checks each valid word letter by letter and stops as soon as a required letter is unavailable. section 19.1
A permutation check should verify that:
- Both lists contain the same elements. section 26.5
- Element counts agree, including repeated elements. section 26.5
- Different ordering does not prevent a match. section 26.5
