diff --git a/solution/2100-2199/2149.Rearrange Array Elements by Sign/README.md b/solution/2100-2199/2149.Rearrange Array Elements by Sign/README.md
index ef55109061bb1..f0d2d3f0ca2a1 100644
--- a/solution/2100-2199/2149.Rearrange Array Elements by Sign/README.md	
+++ b/solution/2100-2199/2149.Rearrange Array Elements by Sign/README.md	
@@ -76,7 +76,15 @@ nums 中的正整数是 [3,1,2] ，负整数是 [-2,-5,-4] 。
 
 <!-- solution:start -->
 
-### 方法一
+### 方法一：双指针
+
+我们先创建一个长度为 $n$ 的数组 $\textit{ans}$，然后使用两个指针 $i$ 和 $j$ 分别指向 $\textit{ans}$ 的偶数下标和奇数下标，初始时 $i = 0$, $j = 1$。
+
+遍历数组 $\textit{nums}$，如果当前元素 $x$ 为正整数，则将 $x$ 放入 $\textit{ans}[i]$，并将 $i$ 增加 $2$；否则将 $x$ 放入 $\textit{ans}[j]$，并将 $j$ 增加 $2$。
+
+最后返回 $\textit{ans}$ 即可。
+
+时间复杂度 $O(n)$，空间复杂度 $O(n)$。其中 $n$ 为数组 $\textit{nums}$ 的长度。
 
 <!-- tabs:start -->
 
@@ -87,12 +95,12 @@ class Solution:
     def rearrangeArray(self, nums: List[int]) -> List[int]:
         ans = [0] * len(nums)
         i, j = 0, 1
-        for num in nums:
-            if num > 0:
-                ans[i] = num
+        for x in nums:
+            if x > 0:
+                ans[i] = x
                 i += 2
             else:
-                ans[j] = num
+                ans[j] = x
                 j += 2
         return ans
 ```
@@ -101,16 +109,15 @@ class Solution:
 
 ```java
 class Solution {
-
     public int[] rearrangeArray(int[] nums) {
         int[] ans = new int[nums.length];
         int i = 0, j = 1;
-        for (int num : nums) {
-            if (num > 0) {
-                ans[i] = num;
+        for (int x : nums) {
+            if (x > 0) {
+                ans[i] = x;
                 i += 2;
             } else {
-                ans[j] = num;
+                ans[j] = x;
                 j += 2;
             }
         }
@@ -127,12 +134,12 @@ public:
     vector<int> rearrangeArray(vector<int>& nums) {
         vector<int> ans(nums.size());
         int i = 0, j = 1;
-        for (int num : nums) {
-            if (num > 0) {
-                ans[i] = num;
+        for (int x : nums) {
+            if (x > 0) {
+                ans[i] = x;
                 i += 2;
             } else {
-                ans[j] = num;
+                ans[j] = x;
                 j += 2;
             }
         }
@@ -147,12 +154,12 @@ public:
 func rearrangeArray(nums []int) []int {
 	ans := make([]int, len(nums))
 	i, j := 0, 1
-	for _, num := range nums {
-		if num > 0 {
-			ans[i] = num
+	for _, x := range nums {
+		if x > 0 {
+			ans[i] = x
 			i += 2
 		} else {
-			ans[j] = num
+			ans[j] = x
 			j += 2
 		}
 	}
@@ -164,15 +171,14 @@ func rearrangeArray(nums []int) []int {
 
 ```ts
 function rearrangeArray(nums: number[]): number[] {
-    let ans = [];
-    let i = 0,
-        j = 1;
-    for (let num of nums) {
-        if (num > 0) {
-            ans[i] = num;
+    const ans: number[] = Array(nums.length);
+    let [i, j] = [0, 1];
+    for (const x of nums) {
+        if (x > 0) {
+            ans[i] = x;
             i += 2;
         } else {
-            ans[j] = num;
+            ans[j] = x;
             j += 2;
         }
     }
diff --git a/solution/2100-2199/2149.Rearrange Array Elements by Sign/README_EN.md b/solution/2100-2199/2149.Rearrange Array Elements by Sign/README_EN.md
index e7b040c53704d..efaf2d931dd35 100644
--- a/solution/2100-2199/2149.Rearrange Array Elements by Sign/README_EN.md	
+++ b/solution/2100-2199/2149.Rearrange Array Elements by Sign/README_EN.md	
@@ -73,7 +73,15 @@ It is not required to do the modifications in-place.
 
 <!-- solution:start -->
 
-### Solution 1
+### Solution 1: Two Pointers
+
+First, we create an array $\textit{ans}$ of length $n$. Then, we use two pointers $i$ and $j$ to point to the even and odd indices of $\textit{ans}$, respectively, with initial values $i = 0$, $j = 1$.
+
+We iterate through the array $\textit{nums}$. If the current element $x$ is a positive integer, then we place $x$ into $\textit{ans}[i]$ and increase $i$ by $2$; otherwise, we place $x$ into $\textit{ans}[j]$ and increase $j$ by $2$.
+
+Finally, we return $\textit{ans}$.
+
+The time complexity is $O(n)$, and the space complexity is $O(n)$. Here, $n$ is the length of the array $\textit{nums}$.
 
 <!-- tabs:start -->
 
@@ -84,12 +92,12 @@ class Solution:
     def rearrangeArray(self, nums: List[int]) -> List[int]:
         ans = [0] * len(nums)
         i, j = 0, 1
-        for num in nums:
-            if num > 0:
-                ans[i] = num
+        for x in nums:
+            if x > 0:
+                ans[i] = x
                 i += 2
             else:
-                ans[j] = num
+                ans[j] = x
                 j += 2
         return ans
 ```
@@ -98,16 +106,15 @@ class Solution:
 
 ```java
 class Solution {
-
     public int[] rearrangeArray(int[] nums) {
         int[] ans = new int[nums.length];
         int i = 0, j = 1;
-        for (int num : nums) {
-            if (num > 0) {
-                ans[i] = num;
+        for (int x : nums) {
+            if (x > 0) {
+                ans[i] = x;
                 i += 2;
             } else {
-                ans[j] = num;
+                ans[j] = x;
                 j += 2;
             }
         }
@@ -124,12 +131,12 @@ public:
     vector<int> rearrangeArray(vector<int>& nums) {
         vector<int> ans(nums.size());
         int i = 0, j = 1;
-        for (int num : nums) {
-            if (num > 0) {
-                ans[i] = num;
+        for (int x : nums) {
+            if (x > 0) {
+                ans[i] = x;
                 i += 2;
             } else {
-                ans[j] = num;
+                ans[j] = x;
                 j += 2;
             }
         }
@@ -144,12 +151,12 @@ public:
 func rearrangeArray(nums []int) []int {
 	ans := make([]int, len(nums))
 	i, j := 0, 1
-	for _, num := range nums {
-		if num > 0 {
-			ans[i] = num
+	for _, x := range nums {
+		if x > 0 {
+			ans[i] = x
 			i += 2
 		} else {
-			ans[j] = num
+			ans[j] = x
 			j += 2
 		}
 	}
@@ -161,15 +168,14 @@ func rearrangeArray(nums []int) []int {
 
 ```ts
 function rearrangeArray(nums: number[]): number[] {
-    let ans = [];
-    let i = 0,
-        j = 1;
-    for (let num of nums) {
-        if (num > 0) {
-            ans[i] = num;
+    const ans: number[] = Array(nums.length);
+    let [i, j] = [0, 1];
+    for (const x of nums) {
+        if (x > 0) {
+            ans[i] = x;
             i += 2;
         } else {
-            ans[j] = num;
+            ans[j] = x;
             j += 2;
         }
     }
diff --git a/solution/2100-2199/2149.Rearrange Array Elements by Sign/Solution.cpp b/solution/2100-2199/2149.Rearrange Array Elements by Sign/Solution.cpp
index 3cf5a6c6805d4..ef006cab32aea 100644
--- a/solution/2100-2199/2149.Rearrange Array Elements by Sign/Solution.cpp	
+++ b/solution/2100-2199/2149.Rearrange Array Elements by Sign/Solution.cpp	
@@ -3,12 +3,12 @@ class Solution {
     vector<int> rearrangeArray(vector<int>& nums) {
         vector<int> ans(nums.size());
         int i = 0, j = 1;
-        for (int num : nums) {
-            if (num > 0) {
-                ans[i] = num;
+        for (int x : nums) {
+            if (x > 0) {
+                ans[i] = x;
                 i += 2;
             } else {
-                ans[j] = num;
+                ans[j] = x;
                 j += 2;
             }
         }
diff --git a/solution/2100-2199/2149.Rearrange Array Elements by Sign/Solution.go b/solution/2100-2199/2149.Rearrange Array Elements by Sign/Solution.go
index 21dc6cb2ea3a3..69a4188de2467 100644
--- a/solution/2100-2199/2149.Rearrange Array Elements by Sign/Solution.go	
+++ b/solution/2100-2199/2149.Rearrange Array Elements by Sign/Solution.go	
@@ -1,12 +1,12 @@
 func rearrangeArray(nums []int) []int {
 	ans := make([]int, len(nums))
 	i, j := 0, 1
-	for _, num := range nums {
-		if num > 0 {
-			ans[i] = num
+	for _, x := range nums {
+		if x > 0 {
+			ans[i] = x
 			i += 2
 		} else {
-			ans[j] = num
+			ans[j] = x
 			j += 2
 		}
 	}
diff --git a/solution/2100-2199/2149.Rearrange Array Elements by Sign/Solution.java b/solution/2100-2199/2149.Rearrange Array Elements by Sign/Solution.java
index e933560968777..2da89d9ca372f 100644
--- a/solution/2100-2199/2149.Rearrange Array Elements by Sign/Solution.java	
+++ b/solution/2100-2199/2149.Rearrange Array Elements by Sign/Solution.java	
@@ -1,14 +1,13 @@
 class Solution {
-
     public int[] rearrangeArray(int[] nums) {
         int[] ans = new int[nums.length];
         int i = 0, j = 1;
-        for (int num : nums) {
-            if (num > 0) {
-                ans[i] = num;
+        for (int x : nums) {
+            if (x > 0) {
+                ans[i] = x;
                 i += 2;
             } else {
-                ans[j] = num;
+                ans[j] = x;
                 j += 2;
             }
         }
diff --git a/solution/2100-2199/2149.Rearrange Array Elements by Sign/Solution.py b/solution/2100-2199/2149.Rearrange Array Elements by Sign/Solution.py
index 54a7aff4a005c..7ec9860e76f4d 100644
--- a/solution/2100-2199/2149.Rearrange Array Elements by Sign/Solution.py	
+++ b/solution/2100-2199/2149.Rearrange Array Elements by Sign/Solution.py	
@@ -2,11 +2,11 @@ class Solution:
     def rearrangeArray(self, nums: List[int]) -> List[int]:
         ans = [0] * len(nums)
         i, j = 0, 1
-        for num in nums:
-            if num > 0:
-                ans[i] = num
+        for x in nums:
+            if x > 0:
+                ans[i] = x
                 i += 2
             else:
-                ans[j] = num
+                ans[j] = x
                 j += 2
         return ans
diff --git a/solution/2100-2199/2149.Rearrange Array Elements by Sign/Solution.ts b/solution/2100-2199/2149.Rearrange Array Elements by Sign/Solution.ts
index b8e40aee94d33..c9f9c64e12ac8 100644
--- a/solution/2100-2199/2149.Rearrange Array Elements by Sign/Solution.ts	
+++ b/solution/2100-2199/2149.Rearrange Array Elements by Sign/Solution.ts	
@@ -1,13 +1,12 @@
 function rearrangeArray(nums: number[]): number[] {
-    let ans = [];
-    let i = 0,
-        j = 1;
-    for (let num of nums) {
-        if (num > 0) {
-            ans[i] = num;
+    const ans: number[] = Array(nums.length);
+    let [i, j] = [0, 1];
+    for (const x of nums) {
+        if (x > 0) {
+            ans[i] = x;
             i += 2;
         } else {
-            ans[j] = num;
+            ans[j] = x;
             j += 2;
         }
     }
diff --git a/solution/2100-2199/2150.Find All Lonely Numbers in the Array/README.md b/solution/2100-2199/2150.Find All Lonely Numbers in the Array/README.md
index 30ca9fd942ca4..6a8a3a4ac5255 100644
--- a/solution/2100-2199/2150.Find All Lonely Numbers in the Array/README.md	
+++ b/solution/2100-2199/2150.Find All Lonely Numbers in the Array/README.md	
@@ -64,7 +64,13 @@ tags:
 
 <!-- solution:start -->
 
-### 方法一
+### 方法一：哈希表
+
+我们用一个哈希表 $\textit{cnt}$ 记录每个数字出现的次数，然后遍历哈希表，对于每个数字及其出现次数 $(x, v)$，如果 $v = 1$ 且 $\textit{cnt}[x - 1] = 0$ 且 $\textit{cnt}[x + 1] = 0$，则 $x$ 是一个孤独数字，将其加入答案数组中。
+
+遍历结束后，返回答案数组即可。
+
+时间复杂度 $O(n)$，空间复杂度 $O(n)$。其中 $n$ 为数组 $\textit{nums}$ 的长度。
 
 <!-- tabs:start -->
 
@@ -73,30 +79,28 @@ tags:
 ```python
 class Solution:
     def findLonely(self, nums: List[int]) -> List[int]:
-        counter = Counter(nums)
-        ans = []
-        for num, cnt in counter.items():
-            if cnt == 1 and counter[num - 1] == 0 and counter[num + 1] == 0:
-                ans.append(num)
-        return ans
+        cnt = Counter(nums)
+        return [
+            x for x, v in cnt.items() if v == 1 and cnt[x - 1] == 0 and cnt[x + 1] == 0
+        ]
 ```
 
 #### Java
 
 ```java
 class Solution {
-
     public List<Integer> findLonely(int[] nums) {
-        Map<Integer, Integer> counter = new HashMap<>();
-        for (int num : nums) {
-            counter.put(num, counter.getOrDefault(num, 0) + 1);
+        Map<Integer, Integer> cnt = new HashMap<>();
+        for (int x : nums) {
+            cnt.merge(x, 1, Integer::sum);
         }
         List<Integer> ans = new ArrayList<>();
-        counter.forEach((k, v) -> {
-            if (v == 1 && !counter.containsKey(k - 1) && !counter.containsKey(k + 1)) {
-                ans.add(k);
+        for (var e : cnt.entrySet()) {
+            int x = e.getKey(), v = e.getValue();
+            if (v == 1 && !cnt.containsKey(x - 1) && !cnt.containsKey(x + 1)) {
+                ans.add(x);
             }
-        });
+        }
         return ans;
     }
 }
@@ -108,12 +112,15 @@ class Solution {
 class Solution {
 public:
     vector<int> findLonely(vector<int>& nums) {
-        unordered_map<int, int> counter;
-        for (int num : nums) ++counter[num];
+        unordered_map<int, int> cnt;
+        for (int x : nums) {
+            cnt[x]++;
+        }
         vector<int> ans;
-        for (auto& e : counter) {
-            int k = e.first, v = e.second;
-            if (v == 1 && !counter.count(k - 1) && !counter.count(k + 1)) ans.push_back(k);
+        for (auto& [x, v] : cnt) {
+            if (v == 1 && !cnt.contains(x - 1) && !cnt.contains(x + 1)) {
+                ans.push_back(x);
+            }
         }
         return ans;
     }
@@ -123,18 +130,17 @@ public:
 #### Go
 
 ```go
-func findLonely(nums []int) []int {
-	counter := make(map[int]int)
-	for _, num := range nums {
-		counter[num]++
+func findLonely(nums []int) (ans []int) {
+	cnt := map[int]int{}
+	for _, x := range nums {
+		cnt[x]++
 	}
-	var ans []int
-	for k, v := range counter {
-		if v == 1 && counter[k-1] == 0 && counter[k+1] == 0 {
-			ans = append(ans, k)
+	for x, v := range cnt {
+		if v == 1 && cnt[x-1] == 0 && cnt[x+1] == 0 {
+			ans = append(ans, x)
 		}
 	}
-	return ans
+	return
 }
 ```
 
@@ -142,14 +148,14 @@ func findLonely(nums []int) []int {
 
 ```ts
 function findLonely(nums: number[]): number[] {
-    let hashMap: Map<number, number> = new Map();
-    for (let num of nums) {
-        hashMap.set(num, (hashMap.get(num) || 0) + 1);
+    const cnt: Map<number, number> = new Map();
+    for (const x of nums) {
+        cnt.set(x, (cnt.get(x) || 0) + 1);
     }
-    let ans: Array<number> = [];
-    for (let [num, count] of hashMap.entries()) {
-        if (count == 1 && !hashMap.get(num - 1) && !hashMap.get(num + 1)) {
-            ans.push(num);
+    const ans: number[] = [];
+    for (const [x, v] of cnt) {
+        if (v === 1 && !cnt.has(x - 1) && !cnt.has(x + 1)) {
+            ans.push(x);
         }
     }
     return ans;
diff --git a/solution/2100-2199/2150.Find All Lonely Numbers in the Array/README_EN.md b/solution/2100-2199/2150.Find All Lonely Numbers in the Array/README_EN.md
index bc490d0563c97..8905b9d5fb939 100644
--- a/solution/2100-2199/2150.Find All Lonely Numbers in the Array/README_EN.md	
+++ b/solution/2100-2199/2150.Find All Lonely Numbers in the Array/README_EN.md	
@@ -65,7 +65,13 @@ Note that [5, 1] may also be returned.
 
 <!-- solution:start -->
 
-### Solution 1
+### Solution 1: Hash Table
+
+We use a hash table $\textit{cnt}$ to record the occurrence count of each number. Then, we iterate through the hash table. For each number and its occurrence count $(x, v)$, if $v = 1$ and $\textit{cnt}[x - 1] = 0$ and $\textit{cnt}[x + 1] = 0$, then $x$ is a lonely number, and we add it to the answer array.
+
+After finishing the iteration, we return the answer array.
+
+The time complexity is $O(n)$, and the space complexity is $O(n)$. Here, $n$ is the length of the array $\textit{nums}$.
 
 <!-- tabs:start -->
 
@@ -74,30 +80,28 @@ Note that [5, 1] may also be returned.
 ```python
 class Solution:
     def findLonely(self, nums: List[int]) -> List[int]:
-        counter = Counter(nums)
-        ans = []
-        for num, cnt in counter.items():
-            if cnt == 1 and counter[num - 1] == 0 and counter[num + 1] == 0:
-                ans.append(num)
-        return ans
+        cnt = Counter(nums)
+        return [
+            x for x, v in cnt.items() if v == 1 and cnt[x - 1] == 0 and cnt[x + 1] == 0
+        ]
 ```
 
 #### Java
 
 ```java
 class Solution {
-
     public List<Integer> findLonely(int[] nums) {
-        Map<Integer, Integer> counter = new HashMap<>();
-        for (int num : nums) {
-            counter.put(num, counter.getOrDefault(num, 0) + 1);
+        Map<Integer, Integer> cnt = new HashMap<>();
+        for (int x : nums) {
+            cnt.merge(x, 1, Integer::sum);
         }
         List<Integer> ans = new ArrayList<>();
-        counter.forEach((k, v) -> {
-            if (v == 1 && !counter.containsKey(k - 1) && !counter.containsKey(k + 1)) {
-                ans.add(k);
+        for (var e : cnt.entrySet()) {
+            int x = e.getKey(), v = e.getValue();
+            if (v == 1 && !cnt.containsKey(x - 1) && !cnt.containsKey(x + 1)) {
+                ans.add(x);
             }
-        });
+        }
         return ans;
     }
 }
@@ -109,12 +113,15 @@ class Solution {
 class Solution {
 public:
     vector<int> findLonely(vector<int>& nums) {
-        unordered_map<int, int> counter;
-        for (int num : nums) ++counter[num];
+        unordered_map<int, int> cnt;
+        for (int x : nums) {
+            cnt[x]++;
+        }
         vector<int> ans;
-        for (auto& e : counter) {
-            int k = e.first, v = e.second;
-            if (v == 1 && !counter.count(k - 1) && !counter.count(k + 1)) ans.push_back(k);
+        for (auto& [x, v] : cnt) {
+            if (v == 1 && !cnt.contains(x - 1) && !cnt.contains(x + 1)) {
+                ans.push_back(x);
+            }
         }
         return ans;
     }
@@ -124,18 +131,17 @@ public:
 #### Go
 
 ```go
-func findLonely(nums []int) []int {
-	counter := make(map[int]int)
-	for _, num := range nums {
-		counter[num]++
+func findLonely(nums []int) (ans []int) {
+	cnt := map[int]int{}
+	for _, x := range nums {
+		cnt[x]++
 	}
-	var ans []int
-	for k, v := range counter {
-		if v == 1 && counter[k-1] == 0 && counter[k+1] == 0 {
-			ans = append(ans, k)
+	for x, v := range cnt {
+		if v == 1 && cnt[x-1] == 0 && cnt[x+1] == 0 {
+			ans = append(ans, x)
 		}
 	}
-	return ans
+	return
 }
 ```
 
@@ -143,14 +149,14 @@ func findLonely(nums []int) []int {
 
 ```ts
 function findLonely(nums: number[]): number[] {
-    let hashMap: Map<number, number> = new Map();
-    for (let num of nums) {
-        hashMap.set(num, (hashMap.get(num) || 0) + 1);
+    const cnt: Map<number, number> = new Map();
+    for (const x of nums) {
+        cnt.set(x, (cnt.get(x) || 0) + 1);
     }
-    let ans: Array<number> = [];
-    for (let [num, count] of hashMap.entries()) {
-        if (count == 1 && !hashMap.get(num - 1) && !hashMap.get(num + 1)) {
-            ans.push(num);
+    const ans: number[] = [];
+    for (const [x, v] of cnt) {
+        if (v === 1 && !cnt.has(x - 1) && !cnt.has(x + 1)) {
+            ans.push(x);
         }
     }
     return ans;
diff --git a/solution/2100-2199/2150.Find All Lonely Numbers in the Array/Solution.cpp b/solution/2100-2199/2150.Find All Lonely Numbers in the Array/Solution.cpp
index 4cdb56deec98d..49e8ae3b1871c 100644
--- a/solution/2100-2199/2150.Find All Lonely Numbers in the Array/Solution.cpp	
+++ b/solution/2100-2199/2150.Find All Lonely Numbers in the Array/Solution.cpp	
@@ -1,12 +1,15 @@
 class Solution {
 public:
     vector<int> findLonely(vector<int>& nums) {
-        unordered_map<int, int> counter;
-        for (int num : nums) ++counter[num];
+        unordered_map<int, int> cnt;
+        for (int x : nums) {
+            cnt[x]++;
+        }
         vector<int> ans;
-        for (auto& e : counter) {
-            int k = e.first, v = e.second;
-            if (v == 1 && !counter.count(k - 1) && !counter.count(k + 1)) ans.push_back(k);
+        for (auto& [x, v] : cnt) {
+            if (v == 1 && !cnt.contains(x - 1) && !cnt.contains(x + 1)) {
+                ans.push_back(x);
+            }
         }
         return ans;
     }
diff --git a/solution/2100-2199/2150.Find All Lonely Numbers in the Array/Solution.go b/solution/2100-2199/2150.Find All Lonely Numbers in the Array/Solution.go
index d8f651526bc11..380a25d4b8284 100644
--- a/solution/2100-2199/2150.Find All Lonely Numbers in the Array/Solution.go	
+++ b/solution/2100-2199/2150.Find All Lonely Numbers in the Array/Solution.go	
@@ -1,13 +1,12 @@
-func findLonely(nums []int) []int {
-	counter := make(map[int]int)
-	for _, num := range nums {
-		counter[num]++
+func findLonely(nums []int) (ans []int) {
+	cnt := map[int]int{}
+	for _, x := range nums {
+		cnt[x]++
 	}
-	var ans []int
-	for k, v := range counter {
-		if v == 1 && counter[k-1] == 0 && counter[k+1] == 0 {
-			ans = append(ans, k)
+	for x, v := range cnt {
+		if v == 1 && cnt[x-1] == 0 && cnt[x+1] == 0 {
+			ans = append(ans, x)
 		}
 	}
-	return ans
+	return
 }
\ No newline at end of file
diff --git a/solution/2100-2199/2150.Find All Lonely Numbers in the Array/Solution.java b/solution/2100-2199/2150.Find All Lonely Numbers in the Array/Solution.java
index 6ac1cd88650ce..34a22b0321dad 100644
--- a/solution/2100-2199/2150.Find All Lonely Numbers in the Array/Solution.java	
+++ b/solution/2100-2199/2150.Find All Lonely Numbers in the Array/Solution.java	
@@ -1,16 +1,16 @@
 class Solution {
-
     public List<Integer> findLonely(int[] nums) {
-        Map<Integer, Integer> counter = new HashMap<>();
-        for (int num : nums) {
-            counter.put(num, counter.getOrDefault(num, 0) + 1);
+        Map<Integer, Integer> cnt = new HashMap<>();
+        for (int x : nums) {
+            cnt.merge(x, 1, Integer::sum);
         }
         List<Integer> ans = new ArrayList<>();
-        counter.forEach((k, v) -> {
-            if (v == 1 && !counter.containsKey(k - 1) && !counter.containsKey(k + 1)) {
-                ans.add(k);
+        for (var e : cnt.entrySet()) {
+            int x = e.getKey(), v = e.getValue();
+            if (v == 1 && !cnt.containsKey(x - 1) && !cnt.containsKey(x + 1)) {
+                ans.add(x);
             }
-        });
+        }
         return ans;
     }
 }
\ No newline at end of file
diff --git a/solution/2100-2199/2150.Find All Lonely Numbers in the Array/Solution.py b/solution/2100-2199/2150.Find All Lonely Numbers in the Array/Solution.py
index 6bc384044f1ac..945eea586c78a 100644
--- a/solution/2100-2199/2150.Find All Lonely Numbers in the Array/Solution.py	
+++ b/solution/2100-2199/2150.Find All Lonely Numbers in the Array/Solution.py	
@@ -1,8 +1,6 @@
 class Solution:
     def findLonely(self, nums: List[int]) -> List[int]:
-        counter = Counter(nums)
-        ans = []
-        for num, cnt in counter.items():
-            if cnt == 1 and counter[num - 1] == 0 and counter[num + 1] == 0:
-                ans.append(num)
-        return ans
+        cnt = Counter(nums)
+        return [
+            x for x, v in cnt.items() if v == 1 and cnt[x - 1] == 0 and cnt[x + 1] == 0
+        ]
diff --git a/solution/2100-2199/2150.Find All Lonely Numbers in the Array/Solution.ts b/solution/2100-2199/2150.Find All Lonely Numbers in the Array/Solution.ts
index 44c85163005a1..561ea0f3cfb77 100644
--- a/solution/2100-2199/2150.Find All Lonely Numbers in the Array/Solution.ts	
+++ b/solution/2100-2199/2150.Find All Lonely Numbers in the Array/Solution.ts	
@@ -1,12 +1,12 @@
 function findLonely(nums: number[]): number[] {
-    let hashMap: Map<number, number> = new Map();
-    for (let num of nums) {
-        hashMap.set(num, (hashMap.get(num) || 0) + 1);
+    const cnt: Map<number, number> = new Map();
+    for (const x of nums) {
+        cnt.set(x, (cnt.get(x) || 0) + 1);
     }
-    let ans: Array<number> = [];
-    for (let [num, count] of hashMap.entries()) {
-        if (count == 1 && !hashMap.get(num - 1) && !hashMap.get(num + 1)) {
-            ans.push(num);
+    const ans: number[] = [];
+    for (const [x, v] of cnt) {
+        if (v === 1 && !cnt.has(x - 1) && !cnt.has(x + 1)) {
+            ans.push(x);
         }
     }
     return ans;