{"id":9290,"date":"2021-12-30T22:07:37","date_gmt":"2021-12-31T06:07:37","guid":{"rendered":"https:\/\/zxi.mytechroad.com\/blog\/?p=9290"},"modified":"2021-12-30T22:21:56","modified_gmt":"2021-12-31T06:21:56","slug":"leetcode-1929-concatenation-of-array","status":"publish","type":"post","link":"https:\/\/zxi.mytechroad.com\/blog\/algorithms\/array\/leetcode-1929-concatenation-of-array\/","title":{"rendered":"\u82b1\u82b1\u9171 LeetCode 1929. Concatenation of Array"},"content":{"rendered":"\n

Given an integer array nums<\/code> of length n<\/code>, you want to create an array ans<\/code> of length 2n<\/code> where ans[i] == nums[i]<\/code> and ans[i + n] == nums[i]<\/code> for 0 <= i < n<\/code> (0-indexed<\/strong>).<\/p>\n\n\n\n

Specifically, ans<\/code> is the concatenation<\/strong> of two nums<\/code> arrays.<\/p>\n\n\n\n

Return the array <\/em>ans<\/code>.<\/p>\n\n\n\n

Example 1:<\/strong><\/p>\n\n\n\n

Input:<\/strong> nums = [1,2,1]\nOutput:<\/strong> [1,2,1,1,2,1]\nExplanation:<\/strong> The array ans is formed as follows:\n- ans = [nums[0],nums[1],nums[2],nums[0],nums[1],nums[2]]\n- ans = [1,2,1,1,2,1]<\/pre>\n\n\n\n
Example 2:<\/strong><\/p>\n\n\n\n
Input:<\/strong> nums = [1,3,2,1]\nOutput:<\/strong> [1,3,2,1,1,3,2,1]\nExplanation:<\/strong> The array ans is formed as follows:\n- ans = [nums[0],nums[1],nums[2],nums[3],nums[0],nums[1],nums[2],nums[3]]\n- ans = [1,3,2,1,1,3,2,1]\n<\/pre>\n\n\n\n
Constraints:<\/strong><\/p>\n\n\n\n
  • n == nums.length<\/code><\/li>
  • 1 <= n <= 1000<\/code><\/li>
  • 1 <= nums[i] <= 1000<\/code><\/li><\/ul>\n\n\n\n
    Solution: Pre-allocation<\/strong><\/h2>\n\n\n\n
    Pre-allocate an array of length 2 * n.
    ans[i] = nums[i % n]<\/p>\n\n\n\n
    Time complexity: O(n)
    Space complexity: O(n)<\/p>\n\n\n\n
    \n
    C++<\/h2>\n
    \n\n
    \n\/\/ Author: Huahua\nclass Solution {\npublic:\n  vector getConcatenation(vector& nums) {\n    const int n = nums.size();\n    vector ans(2 * n);\n    for (int i = 0; i < 2 * n; ++i)\n      ans[i] = nums[i % n];\n    return ans;\n  }\n};\n<\/pre>\n<\/div><\/div>\n","protected":false},"excerpt":{"rendered":"
    Given an integer array nums of length n, you want to create an array ans of length 2n where ans[i] == nums[i] and ans[i + n] == nums[i] for 0 <= i < n (0-indexed). Specifically, ans is the concatenation of two nums arrays.…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[184],"tags":[20,222],"class_list":["post-9290","post","type-post","status-publish","format-standard","hentry","category-array","tag-array","tag-easy","entry","simple"],"_links":{"self":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/9290","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/comments?post=9290"}],"version-history":[{"count":2,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/9290\/revisions"}],"predecessor-version":[{"id":9292,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/9290\/revisions\/9292"}],"wp:attachment":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/media?parent=9290"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/categories?post=9290"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/tags?post=9290"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}