标签：des style blog color os io java ar strong
Given two words (start and end), and a dictionary, find the length of shortest transformation sequence from start to end, such that:
For example,
Given:
start = "hit"
end = "cog"
dict = ["hot","dot","dog","lot","log"]
As one shortest transformation is "hit" -> "hot" -> "dot" -> "dog" -> "cog",
return its length 5.
Note:
public class Solution {
public int ladderLength(String start, String end, Set<String> dict) {
if(dict==null||dict.size()==0)
{
return 0;
}
if(!dict.contains(start)||!dict.contains(end))
{
return 0;
}
if(start==end)
{
return 1;
}
LinkedList<String> queue=new LinkedList<String>();
Set<String> visited=new HashSet<String>(dict.size()*2);
Map<String,Integer> len=new HashMap<String,Integer>(dict.size()*2);
queue.add(start);
visited.add(start);
len.put(start,1);
for(String p=queue.poll();p!=null;p=queue.poll())
{
int LEN=len.get(p);
for(int i=0;i<p.length();i++)
{
StringBuilder builder=new StringBuilder(p);
for(char c='a';c<='z';c++)
{
builder.setCharAt(i,c);
String dest=builder.toString();
if(dict.contains(dest)&&!visited.contains(dest))
{
visited.add(dest);
queue.add(dest);
len.put(dest,LEN+1);
if(dest.equals(end))
{
return LEN+1;
}
}
}
}
}
return 0;
}
}标签：des style blog color os io java ar strong
原文地址：http://blog.csdn.net/jiewuyou/article/details/39179849
