{"id":8131,"date":"2021-02-20T16:32:23","date_gmt":"2021-02-21T00:32:23","guid":{"rendered":"https:\/\/zxi.mytechroad.com\/blog\/?p=8131"},"modified":"2021-02-20T17:39:52","modified_gmt":"2021-02-21T01:39:52","slug":"leetcode-1764-form-array-by-concatenating-subarrays-of-another-array","status":"publish","type":"post","link":"https:\/\/zxi.mytechroad.com\/blog\/algorithms\/array\/leetcode-1764-form-array-by-concatenating-subarrays-of-another-array\/","title":{"rendered":"\u82b1\u82b1\u9171 LeetCode 1764. Form Array by Concatenating Subarrays of Another Array"},"content":{"rendered":"\n

You are given a 2D integer array groups<\/code> of length n<\/code>. You are also given an integer array nums<\/code>.<\/p>\n\n\n\n

You are asked if you can choose n<\/code> disjoint <\/strong>subarrays from the array nums<\/code> such that the ith<\/sup><\/code> subarray is equal to groups[i]<\/code> (0-indexed<\/strong>), and if i > 0<\/code>, the (i-1)th<\/sup><\/code> subarray appears before<\/strong> the ith<\/sup><\/code> subarray in nums<\/code> (i.e. the subarrays must be in the same order as groups<\/code>).<\/p>\n\n\n\n

Return true<\/code> if you can do this task, and<\/em> false<\/code> otherwise<\/em>.<\/p>\n\n\n\n

Note that the subarrays are disjoint<\/strong> if and only if there is no index k<\/code> such that nums[k]<\/code> belongs to more than one subarray. A subarray is a contiguous sequence of elements within an array.<\/p>\n\n\n\n

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

Input:<\/strong> groups = [[1,-1,-1],[3,-2,0]], nums = [1,-1,0,1,-1,-1,3,-2,0]\nOutput:<\/strong> true\nExplanation:<\/strong> You can choose the 0th<\/sup> subarray as [1,-1,0,1,-1,-1<\/strong>,3,-2,0] and the 1st<\/sup> one as [1,-1,0,1,-1,-1,3,-2,0<\/strong>].\nThese subarrays are disjoint as they share no common nums[k] element.\n<\/pre>\n\n\n\n
Example 2:<\/strong><\/p>\n\n\n\n
Input:<\/strong> groups = [[10,-2],[1,2,3,4]], nums = [1,2,3,4,10,-2]\nOutput:<\/strong> false\nExplanation: <\/strong>Note that choosing the subarrays [1,2,3,4<\/strong>,10,-2] and [1,2,3,4,10,-2<\/strong>] is incorrect because they are not in the same order as in groups.\n[10,-2] must come before [1,2,3,4].\n<\/pre>\n\n\n\n
Example 3:<\/strong><\/p>\n\n\n\n
Input:<\/strong> groups = [[1,2,3],[3,4]], nums = [7,7,1,2,3,4,7,7]\nOutput:<\/strong> false\nExplanation: <\/strong>Note that choosing the subarrays [7,7,1,2,3<\/strong>,4,7,7] and [7,7,1,2,3,4<\/strong>,7,7] is invalid because they are not disjoint.\nThey share a common elements nums[4] (0-indexed).\n<\/pre>\n\n\n\n
Constraints:<\/strong><\/p>\n\n\n\n
  • groups.length == n<\/code><\/li>
  • 1 <= n <= 103<\/sup><\/code><\/li>
  • 1 <= groups[i].length, sum(groups[i].length) <= 103<\/sup><\/code><\/li>
  • 1 <= nums.length <= 103<\/sup><\/code><\/li>
  • -107<\/sup> <= groups[i][j], nums[k] <= 107<\/sup><\/code><\/li><\/ul>\n\n\n\n
    <\/p>\n\n\n\n
    Solution: Brute Force<\/strong><\/h2>\n\n\n\n
    Time complexity: O(n^2?)
    Space complexity: O(1)<\/p>\n\n\n\n
    \n
    C++<\/h2>\n
    \n\n
    \n\/\/ Author: Huahua\nclass Solution {\npublic:\n  bool canChoose(vector>& groups, vector& nums) {\n    const int n = nums.size();\n    int s = 0;\n    for (const auto& g : groups) {\n      bool found = false;\n      for (int i = s; i <= n - g.size(); ++i)\n        if (equal(begin(g), end(g), begin(nums) + i)) {\n          s = i + g.size();\n          found = true;\n          break;\n        }\n      if (!found) return false;\n    }\n    return true;\n  }\n};\n<\/pre>\n<\/div><\/div>\n","protected":false},"excerpt":{"rendered":"
    You are given a 2D integer array groups of length n. You are also given an integer array nums. You are asked if you can choose n disjoint subarrays from the array nums such…<\/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":[20,572,410,97,4],"class_list":["post-8131","post","type-post","status-publish","format-standard","hentry","category-array","tag-array","tag-kmp","tag-matching","tag-prefix","tag-string","entry","simple"],"_links":{"self":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/8131","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=8131"}],"version-history":[{"count":2,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/8131\/revisions"}],"predecessor-version":[{"id":8133,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/8131\/revisions\/8133"}],"wp:attachment":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/media?parent=8131"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/categories?post=8131"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/tags?post=8131"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}