(Java) Leetcode 433. Minimum genetic mutation--minimal gene change

A gene string can be represented by an 8-character long string, with choices from "A" , "C" , "G" , "T" .

Suppose we need to investigate on a mutation (mutation from ' start ' to ' end '), where one mutation is defined as one sin GLE character changed in the gene string.

For example, "AACCGGTT" is "AACCGGTA" 1 mutation.

Also, there is a given gene "bank", which records all the valid gene mutations. A gene must is in the bank to make it a valid gene string.

Now, given 3 Things-start, end, bank, your task was to determine what's the minimum number of mutations needed to mutate From ' Start ' to ' end '. If There is no such a mutation, return-1.

Note:

1. Starting point was assumed to being valid, so it might not being included in the bank.
2. If multiple mutations is needed, all mutations during in the sequence must is valid.
3. Assume start and end string is not the same.

Example 1:

Start: "AACCGGTT" End:   "AACCGGTA" bank: ["Aaccggta"]return:1

Example 2:

Start: "AACCGGTT" End:   "AAACGGTA" bank: ["Aaccggta", "Aaccgcta", "Aaacggta"]return:2

Example 3:

Start: "AAAAACCC" End:   "AACCCCCC" bank: ["AAAACCCC", "AAACCCCC", "AACCCCCC"]return:3

The subject and Leetcode 127. Word ladder--Word solitaire is exactly the same, without any difference, using breadth-first search to find the shortest path. be gratified to write code over and over, direct AC.

Java

classSolution { Public intminmutation (string start, String end, string[] bank) {if(Bank = =NULL|| Bank.length = = 0)return-1; Char[] Gen = {' A ', ' C ', ' G ', ' T '}; HashSet<String> Bankset =NewHashset<>();  for(String S:bank) Bankset.add (s); Queue<String> q =NewLinkedlist<>(); HashMap<string, integer> res =NewHashmap<>(); Res.put (Start,0);        Q.add (start);  while(!Q.isempty ()) {String s=Q.poll ();            Bankset.remove (s);  for(inti = 0; I < s.length (); i++) {                Char[] Next =S.tochararray ();  for(CharC:gen) {Next[i]=C; String nexts=NewString (next); if(Bankset.contains (nexts)) {res.put (nexts, Res.get (s)+ 1); if(Nexts.equals (end))returnRes.get (nexts);                    Q.add (nexts); }                }            }        }        return-1; }}

(Java) Leetcode 433. Minimum genetic mutation--minimal gene change