afraah :
I'm having trouble understanding how the last line of code is valid.
class Solution {
public List<List<String>> groupAnagrams(String[] strs) {
if (strs.length == 0) return new ArrayList();
Map<String, List> ans = new HashMap<String, List>();
for (String s : strs) {
char[] ca = s.toCharArray();
Arrays.sort(ca);
String key = String.valueOf(ca);
if (!ans.containsKey(key)) ans.put(key, new ArrayList());
ans.get(key).add(s);
}
return new ArrayList(ans.values());
}
}
The line of code: " return new ArrayList(ans.values());" Are the values being inserted one by one- what exactly is happening?
Traian GEICU :
return new ArrayList(ans.values())
Break it down and see each instructions
1. new ArrayList - new object populated with some values
2 ans.values() - values coming from a collection: Map<K,V> and the method is returning all V.
Note V is List and all V should be a concatenation of all Lists (assume references)
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