From addd3ec1d96974432df05ac90d621bd9d5f4e395 Mon Sep 17 00:00:00 2001
From: 10kartik <kartik@plgworks.com>
Date: Mon, 19 Sep 2022 19:35:44 +0530
Subject: [PATCH 1/4] feat: Added Algo first unique char in a string.

---
 DIRECTORY.md                             |  1 +
 String/FirstUniqueCharacter.js           | 21 +++++++++++++++++++++
 String/test/FirstUniqueCharacter.test.js |  9 +++++++++
 3 files changed, 31 insertions(+)
 create mode 100644 String/FirstUniqueCharacter.js
 create mode 100644 String/test/FirstUniqueCharacter.test.js

diff --git a/DIRECTORY.md b/DIRECTORY.md
index f2d0bf4fab..2eec03b7b6 100644
--- a/DIRECTORY.md
+++ b/DIRECTORY.md
@@ -299,6 +299,7 @@
   * [CountVowels](String/CountVowels.js)
   * [CreatePermutations](String/CreatePermutations.js)
   * [DiceCoefficient](String/DiceCoefficient.js)
+  * [FirstUniqueCharacter](String/FirstUniqueCharacter.js)
   * [FormatPhoneNumber](String/FormatPhoneNumber.js)
   * [GenerateGUID](String/GenerateGUID.js)
   * [HammingDistance](String/HammingDistance.js)
diff --git a/String/FirstUniqueCharacter.js b/String/FirstUniqueCharacter.js
new file mode 100644
index 0000000000..b3b613c766
--- /dev/null
+++ b/String/FirstUniqueCharacter.js
@@ -0,0 +1,21 @@
+/**
+ * @function firstUniqChar
+ * @description Given a string s, find the first non-repeating character in it and return its index. If it does not exist, return -1.
+ * @param {String} str - The input string
+ * @return {Number} - The index of first unique character.
+ * @example firstUniqChar("javascript") => 0
+ * @example firstUniqChar(""sesquipedalian"") => 3
+ * @example firstUniqChar("aabb") => -1
+ */
+
+const firstUniqChar = (str) => {
+  if (typeof str !== 'string') {
+    throw new TypeError('Argument should be string')
+  }
+  for (let i = 0; i < str.length; ++i) {
+    if (str.indexOf(str[i]) === str.lastIndexOf(str[i])) return i
+  }
+  return -1
+}
+
+export { firstUniqChar }
diff --git a/String/test/FirstUniqueCharacter.test.js b/String/test/FirstUniqueCharacter.test.js
new file mode 100644
index 0000000000..b2bc465018
--- /dev/null
+++ b/String/test/FirstUniqueCharacter.test.js
@@ -0,0 +1,9 @@
+import { firstUniqChar } from '../FirstUniqueCharacter'
+
+describe('firstUniqChar', () => {
+  it('locates the index of first unique character in the string', () => {
+    expect(firstUniqChar('javascript')).toEqual(0)
+    expect(firstUniqChar('sesquipedalian')).toEqual(3)
+    expect(firstUniqChar('aabb')).toEqual(-1)
+  })
+})

From c446fbc4a15a55bf0c85aaeb53b2a1ed5426c3f7 Mon Sep 17 00:00:00 2001
From: 10kartik <kartik@plgworks.com>
Date: Mon, 19 Sep 2022 23:42:28 +0530
Subject: [PATCH 2/4] Optimised algo to linear time complexity

---
 String/FirstUniqueCharacter.js | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/String/FirstUniqueCharacter.js b/String/FirstUniqueCharacter.js
index b3b613c766..804944e30b 100644
--- a/String/FirstUniqueCharacter.js
+++ b/String/FirstUniqueCharacter.js
@@ -1,6 +1,6 @@
 /**
  * @function firstUniqChar
- * @description Given a string s, find the first non-repeating character in it and return its index. If it does not exist, return -1.
+ * @description Given a string str, find the first non-repeating character in it and return its index. If it does not exist, return -1.
  * @param {String} str - The input string
  * @return {Number} - The index of first unique character.
  * @example firstUniqChar("javascript") => 0
@@ -12,8 +12,12 @@ const firstUniqChar = (str) => {
   if (typeof str !== 'string') {
     throw new TypeError('Argument should be string')
   }
-  for (let i = 0; i < str.length; ++i) {
-    if (str.indexOf(str[i]) === str.lastIndexOf(str[i])) return i
+  const count = new Map()
+  for (const char of str) {
+    count[char] ? count[char]++ : count[char] = 1
+  }
+  for (let i = 0; i < str.length; i++) {
+    if (count[str[i]] === 1) return i
   }
   return -1
 }

From fd7e29e5e159c33694590c5eb141609accdf0e47 Mon Sep 17 00:00:00 2001
From: 10kartik <kartik@plgworks.com>
Date: Mon, 19 Sep 2022 23:44:29 +0530
Subject: [PATCH 3/4] removed double quotes

---
 String/FirstUniqueCharacter.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/String/FirstUniqueCharacter.js b/String/FirstUniqueCharacter.js
index 804944e30b..2974f08033 100644
--- a/String/FirstUniqueCharacter.js
+++ b/String/FirstUniqueCharacter.js
@@ -4,7 +4,7 @@
  * @param {String} str - The input string
  * @return {Number} - The index of first unique character.
  * @example firstUniqChar("javascript") => 0
- * @example firstUniqChar(""sesquipedalian"") => 3
+ * @example firstUniqChar("sesquipedalian") => 3
  * @example firstUniqChar("aabb") => -1
  */
 

From 0bd36044318529e3c075ff2e828f35643c1b8e7d Mon Sep 17 00:00:00 2001
From: 10kartik <kartik@plgworks.com>
Date: Tue, 20 Sep 2022 00:21:41 +0530
Subject: [PATCH 4/4] Review changes: if-else logic

---
 String/FirstUniqueCharacter.js | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/String/FirstUniqueCharacter.js b/String/FirstUniqueCharacter.js
index 2974f08033..1bacd83070 100644
--- a/String/FirstUniqueCharacter.js
+++ b/String/FirstUniqueCharacter.js
@@ -13,8 +13,13 @@ const firstUniqChar = (str) => {
     throw new TypeError('Argument should be string')
   }
   const count = new Map()
+
   for (const char of str) {
-    count[char] ? count[char]++ : count[char] = 1
+    if (!count[char]) {
+      count[char] = 1
+    } else {
+      count[char]++
+    }
   }
   for (let i = 0; i < str.length; i++) {
     if (count[str[i]] === 1) return i