From 572e16a098e8877bb5044b713bf02630d26d6775 Mon Sep 17 00:00:00 2001
From: ashudeshwal999 <ashudeshwal999@gmail.com>
Date: Tue, 8 Oct 2019 02:53:04 +0530
Subject: [PATCH] --update : add SuffixTree
---
 README.md &#124; 3 +
 src/_DataStructures_/SuffixTree/index.js &#124; 121 +++++++++++++++++++++++
 2 files changed, 124 insertions(+)
 create mode 100644 src/_DataStructures_/SuffixTree/index.js
diff --git a/README.md b/README.md
index 939f0fa3..0af407ea 100644
--- a/README.md
+++ b/README.md
@@ -34,6 +34,9 @@ Collection of interview questions with Unit Tests. Problems includes Data Struct
 - [Queue](src/_DataStructures_/Queue)
 - [Weave](src/_DataStructures_/Queue/weave)
 
+- [Suffix Tree](src/_DataStructures_/SuffixTree)
+
+
 ### Logical Problems
 
 - [Anagrams](src/_Problems_/anagrams)
diff --git a/src/_DataStructures_/SuffixTree/index.js b/src/_DataStructures_/SuffixTree/index.js
new file mode 100644
index 00000000..3a24308d
--- /dev/null
+++ b/src/_DataStructures_/SuffixTree/index.js
@@ -0,0 +1,121 @@
+/* eslint-disable no-plusplus */
+/*
+Implemented by watching this conceptually video: https://www.youtube.com/watch?v=VA9m_l6LpwI
+
+Suffix for banana are :
+banana
+anana
+nana
+ana
+na
+a
+
+Constructing a suffix tree is O(n*d) where d is length of max string
+
+Searching a suffix of a string is O(d) where d is length of suffix string.
+If found then return the index, else return -1
+
+*/
+
+class Node {
+ constructor(value, isEnd, index) {
+ this.data = value;
+ this.isEnd = isEnd;
+ this.index = index;
+ this.next = new Map();
+ }
+}
+
+class SuffixTree {
+ constructor(string) {
+ this.head = new Node();
+ this.string = string;
+ }
+
+ constructSuffixTree() {
+ const { string } = this;
+ let currentString = '';
+ for (let i = string.length - 1; i>= 0; i -= 1) {
+ currentString = string[i] + currentString;
+ let j = 0;
+ let currentNode = this.head;
+ while (j < currentString.length) {
+ if (!currentNode.next.has(currentString[j])) {
+ currentNode.next.set(currentString[j], new Node(currentString, true, i));
+ break;
+ } else {
+ let k = 0;
+ const partialMatchNode = currentNode.next.get(currentString[j]);
+ const partialMatchString = partialMatchNode.data;
+
+ let matchString = '';
+ while (k < partialMatchString.length && j < currentString.length && partialMatchString[k] === currentString[j]) {
+ matchString += currentString[j];
+ k++;
+ j++;
+ }
+
+ let diffString = '';
+ while (k < partialMatchString.length) {
+ diffString += partialMatchString[k];
+ k++;
+ }
+ partialMatchNode.data = matchString;
+ if (diffString) {
+ partialMatchNode.next.set(diffString[0], new Node(diffString, true, partialMatchNode.index));
+ partialMatchNode.isEnd = false;
+ partialMatchNode.index = null;
+ }
+
+ if (partialMatchNode.next.has(currentString[j])) {
+ currentNode = partialMatchNode;
+ } else {
+ let nextString = '';
+ while (j < currentString.length) {
+ nextString += currentString[j];
+ j++;
+ }
+ partialMatchNode.next.set(nextString[0], new Node(nextString, true, i));
+ break;
+ }
+ }
+ }
+ }
+ }
+
+ findSubstring(string) {
+ if (!this.head.next.has(string[0])) {
+ return -1;
+ }
+
+ let currentNode = this.head.next.get(string[0]);
+ let currentNodeValue = currentNode.data;
+
+ let i = 0; let j = 0;
+
+ while (i < string.length) {
+ j = 0;
+ while (i < string.length && j < currentNodeValue.length && string[i++] === currentNodeValue[j++]);
+
+ if (i === string.length && j === currentNodeValue.length && currentNode.isEnd) {
+ return currentNode.index;
+ }
+
+ if (currentNode.next.has(string[i])) {
+ currentNode = currentNode.next.get(string[i]);
+ currentNodeValue = currentNode.data;
+ } else {
+ return -1;
+ }
+ }
+ return -1;
+ }
+}
+
+// const s = new SuffixTree('banana');
+// s.constructSuffixTree();
+
+// console.log(s.findSubstring('nana'));
+
+
+module.exports = SuffixTree;
</div><div class="naked_ctrl">
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<p><a href="http://altstyle.alfasado.net">AltStyle</a> によって変換されたページ <a href="https://patch-diff.githubusercontent.com/raw/knaxus/problem-solving-javascript/pull/45.patch">(-&gt;オリジナル)</a>
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