neetcode-gh · neetcode-gh · Jan 27, 2025 · Jan 24, 2025 · Jan 24, 2025 · Jan 25, 2025
diff --git a/articles/array-with-elements-not-equal-to-average-of-neighbors.md b/articles/array-with-elements-not-equal-to-average-of-neighbors.md
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+## 1. Greedy
+
+::tabs-start
+
+```python
+class Solution:
+    def rearrangeArray(self, nums: List[int]) -> List[int]:
+        nums.sort()
+        res = []
+        l, r = 0, len(nums) - 1
+        while len(res) != len(nums):
+            res.append(nums[l])
+            l += 1
+            if l <= r:
+                res.append(nums[r])
+                r -= 1
+        return res
+```
+
+```java
+public class Solution {
+    public int[] rearrangeArray(int[] nums) {
+        Arrays.sort(nums);
+        int[] res = new int[nums.length];
+        int l = 0, r = nums.length - 1;
+        int idx = 0;
+
+        while (idx != nums.length) {
+            res[idx++] = nums[l++];
+            if (l <= r) {
+                res[idx++] = nums[r--];
+            }
+        }
+
+        return res;
+    }
+}
+```
+
+```cpp
+class Solution {
+public:
+    vector<int> rearrangeArray(vector<int>& nums) {
+        sort(nums.begin(), nums.end());
+        vector<int> res;
+        int l = 0, r = nums.size() - 1;
+
+        while (res.size() != nums.size()) {
+            res.push_back(nums[l++]);
+            if (l <= r) {
+                res.push_back(nums[r--]);
+            }
+        }
+
+        return res;
+    }
+};
+```
+
+```javascript
+class Solution {
+    /**
+     * @param {number[]} nums
+     * @return {number[]}
+     */
+    rearrangeArray(nums) {
+        nums.sort((a, b) => a - b);
+        const res = [];
+        let l = 0, r = nums.length - 1;
+
+        while (res.length !== nums.length) {
+            res.push(nums[l++]);
+            if (l <= r) {
+                res.push(nums[r--]);
+            }
+        }
+
+        return res;
+    }
+}
+```
+
+::tabs-end
+
+### Time & Space Complexity
+
+* Time complexity: $O(n\log n)$
+* Space complexity: $O(n)$
+
+---
+
+## 2. Greedy (Space Optimized)
+
+::tabs-start
+
+```python
+class Solution:
+    def rearrangeArray(self, nums: List[int]) -> List[int]:
+        nums.sort()
+        for i in range(1, len(nums), 2):
+            nums[i], nums[i - 1] = nums[i - 1], nums[i]
+        return nums
+```
+
+```java
+public class Solution {
+    public int[] rearrangeArray(int[] nums) {
+        Arrays.sort(nums);
+        for (int i = 1; i < nums.length; i += 2) {
+            int temp = nums[i];
+            nums[i] = nums[i - 1];
+            nums[i - 1] = temp;
+        }
+        return nums;
+    }
+}
+```
+
+```cpp
+class Solution {
+public:
+    vector<int> rearrangeArray(vector<int>& nums) {
+        sort(nums.begin(), nums.end());
+        for (int i = 1; i < nums.size(); i += 2) {
+            swap(nums[i], nums[i - 1]);
+        }
+        return nums;
+    }
+};
+```
+
+```javascript
+class Solution {
+    /**
+     * @param {number[]} nums
+     * @return {number[]}
+     */
+    rearrangeArray(nums) {
+        nums.sort((a, b) => a - b);
+        for (let i = 1; i < nums.length; i += 2) {
+            [nums[i], nums[i - 1]] = [nums[i - 1], nums[i]];
+        }
+        return nums;
+    }
+}
+```
+
+::tabs-end
+
+### Time & Space Complexity
+
+* Time complexity: $O(n \log n)$
+* Space complexity: $O(1)$ or $O(n)$ depending on the sorting algorithm.
+
+---
+
+## 3. Greedy (Optimal) - I
+
+::tabs-start
+
+```python
+class Solution:
+    def rearrangeArray(self, nums: List[int]) -> List[int]:
+        n = len(nums)
+
+        for i in range(1, n - 1):
+            if 2 * nums[i] == (nums[i - 1] + nums[i + 1]):
+                nums[i], nums[i + 1] = nums[i + 1], nums[i]
+
+        for i in range(n - 2, 0, -1):
+            if 2 * nums[i] == (nums[i - 1] + nums[i + 1]):
+                nums[i], nums[i - 1] = nums[i - 1], nums[i]
+
+        return nums
+```
+
+```java
+public class Solution {
+    public int[] rearrangeArray(int[] nums) {
+        int n = nums.length;
+
+        for (int i = 1; i < n - 1; i++) {
+            if (2 * nums[i] == (nums[i - 1] + nums[i + 1])) {
+                int temp = nums[i];
+                nums[i] = nums[i + 1];
+                nums[i + 1] = temp;
+            }
+        }
+
+        for (int i = n - 2; i > 0; i--) {
+            if (2 * nums[i] == (nums[i - 1] + nums[i + 1])) {
+                int temp = nums[i];
+                nums[i] = nums[i - 1];
+                nums[i - 1] = temp;
+            }
+        }
+
+        return nums;
+    }
+}
+```
+
+```cpp
+class Solution {
+public:
+    vector<int> rearrangeArray(vector<int>& nums) {
+        int n = nums.size();
+
+        for (int i = 1; i < n - 1; i++) {
+            if (2 * nums[i] == (nums[i - 1] + nums[i + 1])) {
+                swap(nums[i], nums[i + 1]);
+            }
+        }
+
+        for (int i = n - 2; i > 0; i--) {
+            if (2 * nums[i] == (nums[i - 1] + nums[i + 1])) {
+                swap(nums[i], nums[i - 1]);
+            }
+        }
+
+        return nums;
+    }
+};
+```
+
+```javascript
+class Solution {
+    /**
+     * @param {number[]} nums
+     * @return {number[]}
+     */
+    rearrangeArray(nums) {
+        const n = nums.length;
+
+        for (let i = 1; i < n - 1; i++) {
+            if (2 * nums[i] === nums[i - 1] + nums[i + 1]) {
+                [nums[i], nums[i + 1]] = [nums[i + 1], nums[i]];
+            }
+        }
+
+        for (let i = n - 2; i > 0; i--) {
+            if (2 * nums[i] === nums[i - 1] + nums[i + 1]) {
+                [nums[i], nums[i - 1]] = [nums[i - 1], nums[i]];
+            }
+        }
+
+        return nums;
+    }
+}
+```
+
+::tabs-end
+
+### Time & Space Complexity
+
+* Time complexity: $O(n)$
+* Space complexity: $O(1)$ extra space.
+
+---
+
+## 4. Greedy Optimal - II
+
+::tabs-start
+
+```python
+class Solution:
+    def rearrangeArray(self, nums: List[int]) -> List[int]:
+        increase = nums[0] < nums[1]
+        for i in range(1, len(nums) - 1):
+            if ((increase and nums[i] < nums[i + 1]) or
+                (not increase and nums[i] > nums[i + 1])
+            ):
+                nums[i], nums[i + 1] = nums[i + 1], nums[i]
+            increase = not increase
+        return nums
+```
+
+```java
+public class Solution {
+    public int[] rearrangeArray(int[] nums) {
+        boolean increase = nums[0] < nums[1];
+        for (int i = 1; i < nums.length - 1; i++) {
+            if ((increase && nums[i] < nums[i + 1]) ||
+                (!increase && nums[i] > nums[i + 1])) {
+                int temp = nums[i];
+                nums[i] = nums[i + 1];
+                nums[i + 1] = temp;
+            }
+            increase = !increase;
+        }
+        return nums;
+    }
+}
+```
+
+```cpp
+class Solution {
+public:
+    vector<int> rearrangeArray(vector<int>& nums) {
+        bool increase = nums[0] < nums[1];
+        for (int i = 1; i < nums.size() - 1; i++) {
+            if ((increase && nums[i] < nums[i + 1]) ||
+                (!increase && nums[i] > nums[i + 1])) {
+                swap(nums[i], nums[i + 1]);
+            }
+            increase = !increase;
+        }
+        return nums;
+    }
+};
+```
+
+```javascript
+class Solution {
+    /**
+     * @param {number[]} nums
+     * @return {number[]}
+     */
+    rearrangeArray(nums) {
+        let increase = nums[0] < nums[1];
+        for (let i = 1; i < nums.length - 1; i++) {
+            if ((increase && nums[i] < nums[i + 1]) ||
+                (!increase && nums[i] > nums[i + 1])) {
+                [nums[i], nums[i + 1]] = [nums[i + 1], nums[i]];
+            }
+            increase = !increase;
+        }
+        return nums;
+    }
+}
+```
+
+::tabs-end
+
+### Time & Space Complexity
+
+* Time complexity: $O(n)$
+* Space complexity: $O(1)$ extra space.