{"id":361,"date":"2020-09-26T10:31:05","date_gmt":"2020-09-26T02:31:05","guid":{"rendered":"http:\/\/39.96.58.60\/?p=361"},"modified":"2022-10-18T16:39:35","modified_gmt":"2022-10-18T08:39:35","slug":"leetcode-77-%e7%bb%84%e5%90%88","status":"publish","type":"post","link":"https:\/\/www.yatenglg.cn\/blog\/?p=361","title":{"rendered":"Leetcode 77. \u7ec4\u5408"},"content":{"rendered":"<p>\u7ed9\u5b9a\u4e24\u4e2a\u6574\u6570 <em>n<\/em> \u548c <em>k<\/em>\uff0c\u8fd4\u56de 1 &#8230; <em>n <\/em>\u4e2d\u6240\u6709\u53ef\u80fd\u7684 <em>k<\/em> \u4e2a\u6570\u7684\u7ec4\u5408\u3002<\/p>\n<p><strong>\u793a\u4f8b:<\/strong><\/p>\n<pre><strong>\u8f93\u5165:<\/strong>&nbsp;n = 4, k = 2\n\n<strong>\u8f93\u51fa:<\/strong>\n\n[\n\n  [2,4],\n\n  [3,4],\n\n  [2,3],\n\n  [1,2],\n\n  [1,3],\n\n  [1,4],\n\n]<\/pre>\n<p>**\u96be\u5ea6**: Medium<\/p>\n<p>**\u6807\u7b7e**: \u56de\u6eaf\u7b97\u6cd5\u3001<\/p>\n<div class=\"hcb_wrap\">\n<pre class=\"prism undefined-numbers lang-python\" data-lang=\"Python\"><code>\n# -*- coding: utf-8 -*-\n# @Author  : LG\n\n\"\"\"\n\u6267\u884c\u7528\u65f6\uff1a652 ms, \u5728\u6240\u6709 Python3 \u63d0\u4ea4\u4e2d\u51fb\u8d25\u4e8617.13% \u7684\u7528\u6237\n\u5185\u5b58\u6d88\u8017\uff1a15.1 MB, \u5728\u6240\u6709 Python3 \u63d0\u4ea4\u4e2d\u51fb\u8d25\u4e8633.38% \u7684\u7528\u6237\n\n\u89e3\u9898\u601d\u8def\uff1a\n    \u56de\u6eaf\n\"\"\"\nclass Solution:\n    def combine(self, n: int, k: int) -&gt; List[List[int]]:\n        nums = list(range(1, n+1))\n        result = []\n        def backtrack(i, current):\n            if len(current) == k:\n                result.append(current[:])\n                return\n            for j in range(i, n):\n                if nums[j] not in current:\n                    current.append(nums[j])\n                    backtrack(j + 1, current)   # \u4e0b\u4e00\u4e2a\n                    current.pop()               # \u56de\u6eaf\n        backtrack(0, [])\n        return result\n\n\"\"\"\n\u6267\u884c\u7528\u65f6\uff1a60 ms, \u5728\u6240\u6709 Python3 \u63d0\u4ea4\u4e2d\u51fb\u8d25\u4e8685.87% \u7684\u7528\u6237\n\u5185\u5b58\u6d88\u8017\uff1a14.9 MB, \u5728\u6240\u6709 Python3 \u63d0\u4ea4\u4e2d\u51fb\u8d25\u4e8683.56% \u7684\u7528\u6237\n\n\u89e3\u9898\u601d\u8def\uff1a\n    \u56de\u6eaf\n    \u5728\u4e0a\u4f8b\u4ee3\u7801\u4e2d\u6dfb\u52a0\u526a\u6c41\u64cd\u4f5c\n    \u5177\u4f53\u5b9e\u73b0\u89c1\u4ee3\u7801\u6ce8\u91ca\n\"\"\"\nclass Solution:\n    def combine(self, n: int, k: int) -&gt; List[List[int]]:\n        nums = list(range(1, n+1))\n        result = []\n        def backtrack(i, current):\n            # print(current)\n            if len(current) == k:\n                result.append(current[:])\n                return\n\n            for j in range(i, n):\n                if n - j &lt; k - len(current):    # n-j \u4e3a\u5f53\u524d\u5269\u4f59\u7684\u6570\u7684\u4e2a\u6570\uff0ck-len(current)\u4e3a\u5f53\u524d\u8fd8\u7f3a\u5c11\u7684\u6570\u91cf\u3002\u5982\u679c\u4e0d\u591f\u65f6\uff0c\u76f4\u63a5\u8df3\u8fc7\u3002\n                    break\n                current.append(nums[j])\n                backtrack(j + 1, current)\n                current.pop()\n        backtrack(0, [])\n        return result<\/code><\/pre>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>\u7ed9\u5b9a\u4e24\u4e2a\u6574\u6570 n \u548c k\uff0c\u8fd4\u56de 1 &#8230; n \u4e2d\u6240\u6709\u53ef\u80fd\u7684 k \u4e2a\u6570\u7684\u7ec4\u5408\u3002 \u793a\u4f8b: \u8f93\u5165:&#038;nbs&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[11,1],"tags":[],"_links":{"self":[{"href":"https:\/\/www.yatenglg.cn\/blog\/index.php?rest_route=\/wp\/v2\/posts\/361"}],"collection":[{"href":"https:\/\/www.yatenglg.cn\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.yatenglg.cn\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.yatenglg.cn\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.yatenglg.cn\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=361"}],"version-history":[{"count":1,"href":"https:\/\/www.yatenglg.cn\/blog\/index.php?rest_route=\/wp\/v2\/posts\/361\/revisions"}],"predecessor-version":[{"id":362,"href":"https:\/\/www.yatenglg.cn\/blog\/index.php?rest_route=\/wp\/v2\/posts\/361\/revisions\/362"}],"wp:attachment":[{"href":"https:\/\/www.yatenglg.cn\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=361"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.yatenglg.cn\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=361"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.yatenglg.cn\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=361"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}