{"id":126,"date":"2018-12-03T10:43:11","date_gmt":"2018-12-03T02:43:11","guid":{"rendered":"https:\/\/www.caiqinyi.cn\/?p=126"},"modified":"2021-04-24T17:04:31","modified_gmt":"2021-04-24T09:04:31","slug":"construct_quad_tree","status":"publish","type":"post","link":"https:\/\/www.caiqinyi.cn\/index.php\/2018\/12\/03\/construct_quad_tree\/","title":{"rendered":"\u6784\u9020\u56db\u53c9\u6811"},"content":{"rendered":"<p>\u7ecf\u5e38\u63a5\u89e6\u7684\u662f\u4e8c\u53c9\u6811, \u5bf9\u56db\u53c9\u6811\u6216\u8005\u516b\u53c9\u6811\u4ec5\u4ec5\u662f\u6709\u6240\u8033\u95fb, \u77e5\u9053\u662f\u5e72\u561b\u7684:<\/p>\n<blockquote><p>\n\u56db\u53c9\u6811\u5e7f\u6cdb\u5e94\u7528\u4e8e\u56fe\u50cf\u5904\u7406\u3001\u7a7a\u95f4\u6570\u636e\u7d22\u5f15\u30012D\u4e2d\u7684\u5feb\u901f\u78b0\u649e\u68c0\u6d4b\u3001\u5b58\u50a8\u7a00\u758f\u6570\u636e\u7b49\uff0c\u800c\u516b\u53c9\u6811\uff08Octree\uff09\u4e3b\u8981\u5e94\u7528\u4e8e3D\u56fe\u5f62\u5904\u7406\u3002\u5bf9\u6e38\u620f\u7f16\u7a0b\uff0c\u8fd9\u4f1a\u5f88\u6709\u7528\u3002\n<\/p><\/blockquote>\n<p><!--more--><\/p>\n<p>\u4f46\u4ece\u672a\u81ea\u5df1\u5b9e\u73b0\u8fc7, \u4eca\u5929\u6765\u7b80\u5355\u5730\u5b9e\u73b0\u4e00\u4e0b\u56db\u53c9\u6811\u7684\u6784\u9020, \u9898\u76ee\u6765\u6e90\u4e8eLeetCode 427. \u601d\u8def\u5f88\u7b80\u5355, \u5176\u5b9e\u5c31\u662f\u9012\u5f52.<\/p>\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"C++\" data-enlighter-theme=\"monokai\">\r\n\/*\r\n\/\/ Definition for a QuadTree node.\r\nclass Node {\r\npublic:\r\n    bool val;\r\n    bool isLeaf;\r\n    Node* topLeft;\r\n    Node* topRight;\r\n    Node* bottomLeft;\r\n    Node* bottomRight;\r\n\r\n    Node() {}\r\n\r\n    Node(bool _val, bool _isLeaf, Node* _topLeft, Node* _topRight, Node* _bottomLeft, Node* _bottomRight) {\r\n        val = _val;\r\n        isLeaf = _isLeaf;\r\n        topLeft = _topLeft;\r\n        topRight = _topRight;\r\n        bottomLeft = _bottomLeft;\r\n        bottomRight = _bottomRight;\r\n    }\r\n};\r\n*\/\r\nclass Solution {\r\npublic:\r\n    Node* construct(vector&lt;vector&lt;int&gt;&gt;& grid) {\r\n        int N=grid.size();\r\n        if(N==0) return nullptr;\r\n        return DFS(grid,0,0,N);\r\n    }\r\n    \r\n    Node* DFS(vector&lt;vector&lt;int&gt;&gt;& grid,int x,int y,int N)\r\n    {\r\n        if(N==1) return new Node(grid[x][y]==1?true:false,true,nullptr,nullptr,nullptr,nullptr);\r\n        N\/=2;\r\n        Node* topLeft=DFS(grid,x,y,N);\r\n        Node* topRight=DFS(grid,x,y+N,N);\r\n        Node* bottomLeft=DFS(grid,x+N,y,N);\r\n        Node* bottomRight=DFS(grid,x+N,y+N,N);\r\n        \r\n        if(topLeft->isLeaf && topRight->isLeaf && bottomLeft->isLeaf && bottomRight->isLeaf && topLeft->val==topRight->val && topRight->val==bottomLeft->val && bottomLeft->val==bottomRight->val)\r\n        {\r\n            bool val=topLeft->val;\r\n            delete topLeft;\r\n            delete topRight;\r\n            delete bottomLeft;\r\n            delete bottomRight;\r\n            return new Node(val,true,nullptr,nullptr,nullptr,nullptr);\r\n        }\r\n        else\r\n            return new Node(true,false,topLeft,topRight,bottomLeft,bottomRight);\r\n    }\r\n};\r\n<\/pre>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/www.caiqinyi.cn\/wp-content\/uploads\/2018\/12\/962_grid_divided-300x81.png\" alt=\"\" width=\"1200\" height=\"324\" class=\"alignnone size-medium wp-image-138\" srcset=\"https:\/\/www.caiqinyi.cn\/wp-content\/uploads\/2018\/12\/962_grid_divided-300x81.png 300w, https:\/\/www.caiqinyi.cn\/wp-content\/uploads\/2018\/12\/962_grid_divided-768x208.png 768w, https:\/\/www.caiqinyi.cn\/wp-content\/uploads\/2018\/12\/962_grid_divided.png 1793w\" sizes=\"(max-width: 1200px) 100vw, 1200px\" \/><\/p>\n<p>\u4e00\u5f00\u59cb\u5fd8\u8bb0\u4e86\u5408\u5e76\u56db\u4e2a\u76f8\u540c\u503c\u7684\u53f6\u5b50\u8282\u70b9, \u5176\u5b9e\u662f\u6709\u5fc5\u8981\u7684, \u56e0\u4e3a\u8fd9\u53ef\u4ee5\u8282\u7701\u4e00\u4e9b\u5185\u5b58\u7a7a\u95f4, \u6574\u4e2a\u7b97\u6cd5\u65f6\u95f4\u590d\u6742\u5ea6\u4e0e\u56db\u53c9\u6811\u7684\u6df1\u5ea6\u6709\u5173, \u5927\u6982\u662fO(lgN). \u7c7b\u4f3c\u5730, \u516b\u53c9\u6811\u4e5f\u662f\u540c\u6837\u7684\u9053\u7406, \u53ea\u4e0d\u8fc7\u76f8\u6bd4\u56db\u53c9\u6811\u800c\u8a00\u6bcf\u4e2a\u8282\u70b9\u81f3\u591a\u591a\u4e86\u56db\u4e2a\u5206\u53c9\u7f62\u4e86~<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u7ecf\u5e38\u63a5\u89e6\u7684\u662f\u4e8c\u53c9\u6811, \u5bf9\u56db\u53c9\u6811\u6216\u8005\u516b\u53c9\u6811\u4ec5\u4ec5\u662f\u6709\u6240\u8033\u95fb, \u77e5\u9053\u662f\u5e72\u561b\u7684: \u56db\u53c9\u6811\u5e7f\u6cdb\u5e94\u7528\u4e8e\u56fe\u50cf\u5904\u7406\u3001\u7a7a\u95f4\u6570\u636e\u7d22 &hellip; <a href=\"https:\/\/www.caiqinyi.cn\/index.php\/2018\/12\/03\/construct_quad_tree\/\" class=\"more-link\">\u7ee7\u7eed\u9605\u8bfb<span class=\"screen-reader-text\">\u6784\u9020\u56db\u53c9\u6811<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[],"_links":{"self":[{"href":"https:\/\/www.caiqinyi.cn\/index.php\/wp-json\/wp\/v2\/posts\/126"}],"collection":[{"href":"https:\/\/www.caiqinyi.cn\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.caiqinyi.cn\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.caiqinyi.cn\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.caiqinyi.cn\/index.php\/wp-json\/wp\/v2\/comments?post=126"}],"version-history":[{"count":13,"href":"https:\/\/www.caiqinyi.cn\/index.php\/wp-json\/wp\/v2\/posts\/126\/revisions"}],"predecessor-version":[{"id":140,"href":"https:\/\/www.caiqinyi.cn\/index.php\/wp-json\/wp\/v2\/posts\/126\/revisions\/140"}],"wp:attachment":[{"href":"https:\/\/www.caiqinyi.cn\/index.php\/wp-json\/wp\/v2\/media?parent=126"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.caiqinyi.cn\/index.php\/wp-json\/wp\/v2\/categories?post=126"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.caiqinyi.cn\/index.php\/wp-json\/wp\/v2\/tags?post=126"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}