From a1a9fd834ce2c71b4eb8c900534ea77c15db45cb Mon Sep 17 00:00:00 2001
From: Nari Jeong <92130993+naringst@users.noreply.github.com>
Date: Wed, 4 Sep 2024 22:54:03 +0900
Subject: [PATCH 1/3] Valid Palindrome Solution

---
 valid-palindrome/naringst.js | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)
 create mode 100644 valid-palindrome/naringst.js

diff --git a/valid-palindrome/naringst.js b/valid-palindrome/naringst.js
new file mode 100644
index 000000000..5007bc9d1
--- /dev/null
+++ b/valid-palindrome/naringst.js
@@ -0,0 +1,29 @@
+/**
+ * @param {string} s
+ * @return {boolean}
+ */
+
+/**
+ * Runtime: 66ms, Memory: 54.75MB
+ * Time complexity: O(s.length)
+ * Space complexity: O(s.length)
+ *
+ */
+
+var isPalindrome = function (s) {
+  let trimmed = s.toLowerCase();
+  let answer = [];
+  let checkAlphabet = /[a-zA-Z]/;
+  let checkNum = /[0-9]/;
+
+  for (let alpha of trimmed) {
+    if (checkAlphabet.test(alpha) || checkNum.test(alpha)) {
+      answer.push(alpha);
+    }
+  }
+
+  if (answer.join("") === answer.reverse().join("")) {
+    return true;
+  }
+  return false;
+};

From ad805186c124a32ec135a91655ec5b02f739150a Mon Sep 17 00:00:00 2001
From: Nari Jeong <92130993+naringst@users.noreply.github.com>
Date: Wed, 4 Sep 2024 23:37:41 +0900
Subject: [PATCH 2/3] Missing Number Solution

---
 missing-number/naringst.js | 45 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 missing-number/naringst.js

diff --git a/missing-number/naringst.js b/missing-number/naringst.js
new file mode 100644
index 000000000..1a20722b9
--- /dev/null
+++ b/missing-number/naringst.js
@@ -0,0 +1,45 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+
+/**
+ * Runtime: 63ms, Memory: 51.68MB
+ * Time complexity: O(nlogn)
+ * Space complexity: O(nlogn)
+ *
+ */
+
+var missingNumber = function (nums) {
+  const n = nums.length;
+  nums.sort((a, b) => a - b);
+
+  if (!nums.includes(0)) {
+    return 0;
+  }
+  for (let i = 0; i < n; i++) {
+    if (nums[i + 1] - nums[i] !== 1) {
+      return nums[i] + 1;
+    }
+  }
+  return nums[-1];
+};
+
+/**
+ * NOTE
+ * if use 'sort()' -> O(nlogn)
+ * if you solve this problem without using sort(), can use sum of nums
+ */
+
+var missingNumber = function (nums) {
+  const sumOfNums = nums.reduce((num, total) => num + total, 0);
+
+  const n = nums.length;
+  const expectedSum = (n * (n + 1)) / 2;
+
+  if (expectedSum === sumOfNums) {
+    return 0;
+  } else {
+    return expectedSum - sumOfNums;
+  }
+};

From 022dd7d0ba12f813433d7d36bc0471a46c56859c Mon Sep 17 00:00:00 2001
From: Nari Jeong <92130993+naringst@users.noreply.github.com>
Date: Wed, 4 Sep 2024 23:40:28 +0900
Subject: [PATCH 3/3] add: missing number better solution

---
 missing-number/naringst.js | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/missing-number/naringst.js b/missing-number/naringst.js
index 1a20722b9..58ff1da97 100644
--- a/missing-number/naringst.js
+++ b/missing-number/naringst.js
@@ -43,3 +43,20 @@ var missingNumber = function (nums) {
     return expectedSum - sumOfNums;
   }
 };
+
+/**
+ * NOTE
+ * or you can subtract while adding
+ */
+
+var missingNumber = function (nums) {
+  let target = 0;
+  for (let i = 0; i <= nums.length; i++) {
+    target += i;
+
+    if (i < nums.length) {
+      target -= nums[i];
+    }
+  }
+  return target;
+};