# 648 Replace Words

### Problem

In English, we have a concept called root, which can be followed by some other words to form another longer word - let's call this word successor. For example, the root an, followed by other, which can form another word another.

Now, given a dictionary consisting of many roots and a sentence. You need to replace all the successor in the sentence with the root forming it. If a successor has many roots can form it, replace it with the root with the shortest length.

You need to output the sentence after the replacement.

Example 1:

``````Input: dict = ["cat", "bat", "rat"]
sentence = "the cattle was rattled by the battery"
Output: "the cat was rat by the bat"
``````

Note:

1. The input will only have lower-case letters.
2. 1 <= dict words number <= 1000
3. 1 <= sentence words number <= 1000
4. 1 <= root length <= 100
5. <= sentence words length <= 1000

### Solutions

``````class Solution {
class Node {
public boolean isLeaf = false;
public HashMap<Character, Node> children = new HashMap<>();
}
class Trie {
private Node root = new Node();
public void add(String word) {
Node node = root;
for (int i = 0; i < word.length(); i ++) {
char c = word.charAt(i);
if (!node.children.containsKey(c)) {
node.children.put(c, new Node());
}
node = node.children.get(c);
if (i == word.length() - 1) {
node.isLeaf = true;
}
}
}
private String shortestPrefix(String word) {
Node node = root;
for (int i = 0; i < word.length(); i ++) {
char c = word.charAt(i);
if (!node.children.containsKey(c)) {
return word;
}
node = node.children.get(c);
if (node.isLeaf == true) {
return word.substring(0, i + 1);
}
}
return word;
}
}
public String replaceWords(List<String> dict, String sentence) {
Trie t = new Trie();
for (String str:dict) {
}

StringBuilder sb = new StringBuilder();
String[] tokens = sentence.split(" ");
for (int i = 0; i < tokens.length; i ++) {
String token = tokens[i];
// String res = shortestPrefix(t, token);
String res = t.shortestPrefix(token);
sb.append(" " + res);
}
if (sb.length() > 0) {
sb.deleteCharAt(0);
}
return sb.toString();
}
}
``````