{"id":6972,"date":"2020-06-27T11:14:42","date_gmt":"2020-06-27T18:14:42","guid":{"rendered":"https:\/\/zxi.mytechroad.com\/blog\/?p=6972"},"modified":"2020-06-27T11:15:12","modified_gmt":"2020-06-27T18:15:12","slug":"leetcode-1492-the-kth-factor-of-n","status":"publish","type":"post","link":"https:\/\/zxi.mytechroad.com\/blog\/algorithms\/array\/leetcode-1492-the-kth-factor-of-n\/","title":{"rendered":"\u82b1\u82b1\u9171 LeetCode 1492. The kth Factor of n"},"content":{"rendered":"\n

Given two positive integers n<\/code> and k<\/code>.<\/p>\n\n\n\n

A factor of an integer n<\/code> is defined as an integer i<\/code> where n % i == 0<\/code>.<\/p>\n\n\n\n

Consider a list of all factors of n<\/code> sorted in ascending order<\/strong>, return the <\/em>kth<\/code> factor<\/em> in this list or return -1<\/strong> if n<\/code> has less than k<\/code> factors.<\/p>\n\n\n\n

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

Input:<\/strong> n = 12, k = 3\nOutput:<\/strong> 3\nExplanation:<\/strong> Factors list is [1, 2, 3, 4, 6, 12], the 3rd factor is 3.\n<\/pre>\n\n\n\n
Example 2:<\/strong><\/p>\n\n\n\n
Input:<\/strong> n = 7, k = 2\nOutput:<\/strong> 7\nExplanation:<\/strong> Factors list is [1, 7], the 2nd factor is 7.\n<\/pre>\n\n\n\n
Example 3:<\/strong><\/p>\n\n\n\n
Input:<\/strong> n = 4, k = 4\nOutput:<\/strong> -1\nExplanation:<\/strong> Factors list is [1, 2, 4], there is only 3 factors. We should return -1.\n<\/pre>\n\n\n\n
Example 4:<\/strong><\/p>\n\n\n\n
Input:<\/strong> n = 1, k = 1\nOutput:<\/strong> 1\nExplanation:<\/strong> Factors list is [1], the 1st factor is 1.\n<\/pre>\n\n\n\n
Example 5:<\/strong><\/p>\n\n\n\n
Input:<\/strong> n = 1000, k = 3\nOutput:<\/strong> 4\nExplanation:<\/strong> Factors list is [1, 2, 4, 5, 8, 10, 20, 25, 40, 50, 100, 125, 200, 250, 500, 1000].\n<\/pre>\n\n\n\n
Constraints:<\/strong><\/p>\n\n\n\n
  • 1 <= k <= n <= 1000<\/code><\/li><\/ul>\n\n\n\n
    Solution: Brute Force<\/strong><\/h2>\n\n\n\n
    Time complexity: O(n)
    Space complexity: O(1)<\/p>\n\n\n\n
    \n
    C++<\/h2>\n
    \n\n
    \n\/\/ Author: Huahua\nclass Solution {\npublic:\n  int kthFactor(int n, int k) {\n    for (int i = 1; i <= n; ++i)\n      if (n % i == 0 && --k == 0) return i;\n    return -1;\n  }\n};\n<\/pre>\n<\/div><\/div>\n","protected":false},"excerpt":{"rendered":"
    Given two positive integers n and k. A factor of an integer n is defined as an integer i where n % i == 0. Consider a list of all factors of n sorted in ascending…<\/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":[441,177],"class_list":["post-6972","post","type-post","status-publish","format-standard","hentry","category-array","tag-factor","tag-medium","entry","simple"],"_links":{"self":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/6972","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=6972"}],"version-history":[{"count":2,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/6972\/revisions"}],"predecessor-version":[{"id":6974,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/6972\/revisions\/6974"}],"wp:attachment":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/media?parent=6972"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/categories?post=6972"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/tags?post=6972"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}