Trie + DFS
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
| class Solution {
private static class Trie {
private static class TrieNode {
private final TrieNode[] children;
private boolean end;
public TrieNode() {
this.children = new TrieNode[26];
}
}
private final TrieNode root;
public Trie() {
this.root = new TrieNode();
}
public void reverseInsert(String word) {
TrieNode node = root;
boolean longest = false;
for (int i = word.length() - 1; i >= 0; i--) {
int offset = word.charAt(i) - 'a';
node.end = false;
if (node.children[offset] == null) {
node.children[offset] = new TrieNode();
longest = true;
}
node = node.children[offset];
}
if (longest) {
node.end = true;
}
}
public int getMinimumLengthEncoding() {
return dfs(root, 0);
}
private int dfs(TrieNode node, int depth) {
if (node.end) {
return depth + 1;
}
int length = 0;
for (TrieNode child : node.children) {
if (child != null) {
length += dfs(child, depth + 1);
}
}
return length;
}
}
public int minimumLengthEncoding(String[] words) {
Trie trie = new Trie();
for (String word : words) {
trie.reverseInsert(word);
}
return trie.getMinimumLengthEncoding();
}
}
|
Trie
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
| class Solution {
private static class Trie {
private static class TrieNode {
private final TrieNode[] children;
public TrieNode() {
this.children = new TrieNode[26];
}
}
private final TrieNode root;
public Trie() {
this.root = new TrieNode();
}
public int reverseInsert(String word) {
TrieNode node = root;
boolean longest = false;
for (int i = word.length() - 1; i >= 0; i--) {
int offset = word.charAt(i) - 'a';
if (node.children[offset] == null) {
node.children[offset] = new TrieNode();
longest = true;
}
node = node.children[offset];
}
return longest ? word.length() + 1 : 0;
}
}
public int minimumLengthEncoding(String[] words) {
int minLength = 0;
Arrays.sort(words, (o1, o2) -> o2.length() - o1.length());
Trie trie = new Trie();
for (String word : words) {
minLength += trie.reverseInsert(word);
}
return minLength;
}
}
|
References
820. Short Encoding of Words
剑指 Offer II 065. 最短的单词编码