Solution

Method 1 - Separate, Sort, and Merge

Intuition

Extract elements at even and odd indices separately, sort them according to their requirements (even indices ascending, odd indices descending), then place them back in their respective positions.

Approach

Separate elements at even indices and odd indices into different arrays
Sort even-indexed elements in ascending order (non-decreasing)
Sort odd-indexed elements in descending order (non-increasing)
Merge the sorted arrays back into the result, maintaining index parity

Code

[{"language":"C++","code":"#include <vector>\n#include <algorithm>\nusing namespace std;\n\nclass Solution {\npublic:\n    vector<int> sortEvenOdd(vector<int>& nums) {\n        vector<int> evenElements, oddElements;\n        \n        // Separate elements by index parity\n        for (int i = 0; i < nums.size(); i++) {\n            if (i % 2 == 0) {\n                evenElements.push_back(nums[i]);\n            } else {\n                oddElements.push_back(nums[i]);\n            }\n        }\n        \n        // Sort even indices in ascending order\n        sort(evenElements.begin(), evenElements.end());\n        \n        // Sort odd indices in descending order\n        sort(oddElements.begin(), oddElements.end(), greater<int>());\n        \n        // Merge back into result\n        vector<int> result(nums.size());\n        int evenIdx = 0, oddIdx = 0;\n        \n        for (int i = 0; i < nums.size(); i++) {\n            if (i % 2 == 0) {\n                result[i] = evenElements[evenIdx++];\n            } else {\n                result[i] = oddElements[oddIdx++];\n            }\n        }\n        \n        return result;\n    }\n};","lang":"cpp","html":"<pre class=\"shiki shiki-themes github-light github-dark\" style=\"background-color:#fff;--shiki-dark-bg:#24292e;color:#24292e;--shiki-dark:#e1e4e8\" tabindex=\"0\"><code><span class=\"line\"><span style=\"color:#D73A49;--shiki-dark:#F97583\">#include</span><span style=\"color:#032F62;--shiki-dark:#9ECBFF\"> &#x3C;vector></span></span>\n<span class=\"line\"><span style=\"color:#D73A49;--shiki-dark:#F97583\">#include</span><span style=\"color:#032F62;--shiki-dark:#9ECBFF\"> &#x3C;algorithm></span></span>\n<span class=\"line\"><span style=\"color:#D73A49;--shiki-dark:#F97583\">using</span><span style=\"color:#D73A49;--shiki-dark:#F97583\"> namespace</span><span style=\"color:#6F42C1;--shiki-dark:#B392F0\"> std</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">;</span></span>\n<span class=\"line\"></span>\n<span class=\"line\"><span style=\"color:#D73A49;--shiki-dark:#F97583\">class</span><span style=\"color:#6F42C1;--shiki-dark:#B392F0\"> Solution</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\"> {</span></span>\n<span class=\"line\"><span style=\"color:#D73A49;--shiki-dark:#F97583\">public:</span></span>\n<span class=\"line\"><span style=\"color:#6F42C1;--shiki-dark:#B392F0\">    vector</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">&#x3C;</span><span style=\"color:#D73A49;--shiki-dark:#F97583\">int</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">> </span><span style=\"color:#6F42C1;--shiki-dark:#B392F0\">sortEvenOdd</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">(</span><span style=\"color:#6F42C1;--shiki-dark:#B392F0\">vector</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">&#x3C;</span><span style=\"color:#D73A49;--shiki-dark:#F97583\">int</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">></span><span style=\"color:#D73A49;--shiki-dark:#F97583\">&#x26;</span

Related Tags