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Commit d25eff4

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appleJaxtrekhleb
authored andcommitted
Add Trie.deleteWord and TrieNode.removeChild (trekhleb#181)
1 parent 6e2ff9b commit d25eff4

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4 files changed

+96
-0
lines changed

4 files changed

+96
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lines changed

‎src/data-structures/trie/Trie.js‎

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Original file line numberDiff line numberDiff line change
@@ -24,6 +24,35 @@ export default class Trie {
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return this;
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}
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/**
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* @param {string} word
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* @return {Trie}
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*/
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deleteWord(word) {
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function depthFirstDelete(currentNode, charIndex) {
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if (charIndex >= word.length) return;
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const character = word[charIndex];
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const nextNode = currentNode.getChild(character);
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if (nextNode == null) return;
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depthFirstDelete(nextNode, charIndex + 1);
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if (charIndex === word.length - 1) {
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nextNode.isCompleteWord = false;
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}
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// childNode is deleted only if:
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// - childNode has NO children
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// - childNode.isCompleteWord === false
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currentNode.removeChild(character);
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}
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depthFirstDelete(this.head, 0);
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return this;
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}
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/**
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* @param {string} word
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* @return {string[]}

‎src/data-structures/trie/TrieNode.js‎

Lines changed: 25 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -37,6 +37,31 @@ export default class TrieNode {
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return childNode;
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}
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/**
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* @param {string} character
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* @return {TrieNode}
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*/
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removeChild(character) {
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function isSafeToDelete(node) {
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return (
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node
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&& !node.isCompleteWord
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&& node.children.getKeys().length === 0
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);
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}
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const childNode = this.getChild(character);
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// delete childNode only if:
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// - childNode has NO children
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// - childNode.isCompleteWord === false
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if (isSafeToDelete(childNode)) {
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this.children.delete(character);
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}
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return this;
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}
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/**
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* @param {string} character
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* @return {boolean}

‎src/data-structures/trie/__test__/Trie.test.js‎

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Original file line numberDiff line numberDiff line change
@@ -23,6 +23,18 @@ describe('Trie', () => {
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expect(trie.head.getChild('c').getChild('a').getChild('t').toString()).toBe('t*');
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});
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it('should delete words from trie', () => {
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const trie = new Trie();
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trie.addWord('carpet');
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trie.addWord('car');
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expect(trie.doesWordExist('carpet')).toBe(true);
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trie.deleteWord('carpet');
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expect(trie.doesWordExist('carpet')).toEqual(false);
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expect(trie.doesWordExist('car')).toEqual(true);
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});
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it('should suggests next characters', () => {
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const trie = new Trie();
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‎src/data-structures/trie/__test__/TrieNode.test.js‎

Lines changed: 30 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -18,6 +18,36 @@ describe('TrieNode', () => {
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expect(trieNode.toString()).toBe('c:a,o');
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});
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describe('removing child nodes', () => {
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it('should delete child node if the child node has NO children', () => {
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const trieNode = new TrieNode('c');
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trieNode.addChild('a');
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expect(trieNode.hasChild('a')).toBe(true);
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trieNode.removeChild('a');
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expect(trieNode.hasChild('a')).toBe(false);
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});
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it('should NOT delete child node if the child node has children', () => {
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const trieNode = new TrieNode('c');
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trieNode.addChild('a');
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const childNode = trieNode.getChild('a');
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childNode.addChild('r');
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trieNode.removeChild('a');
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expect(trieNode.hasChild('a')).toEqual(true);
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});
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it('should NOT delete child node if the child node completes a word', () => {
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const trieNode = new TrieNode('c');
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const IS_COMPLETE_WORD = true;
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trieNode.addChild('a', IS_COMPLETE_WORD);
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trieNode.removeChild('a');
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expect(trieNode.hasChild('a')).toEqual(true);
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});
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});
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it('should get child nodes', () => {
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const trieNode = new TrieNode('c');
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