{"id":1699,"date":"2021-06-01T20:26:17","date_gmt":"2021-06-01T12:26:17","guid":{"rendered":"http:\/\/lonelinerd.com\/?p=1699"},"modified":"2021-06-01T23:17:27","modified_gmt":"2021-06-01T15:17:27","slug":"leetcode-695","status":"publish","type":"post","link":"https:\/\/lonelinerd.com\/index.php\/2021\/06\/01\/leetcode-695\/","title":{"rendered":"[LeetCode\u5237\u984c\u7b46\u8a18] 695 \u2013 Max Area of Island"},"content":{"rendered":"\t\t
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\u984c\u76ee\u63cf\u8ff0\uff1a<\/strong><\/span><\/h4>

You are given an <\/span>m x n<\/code><\/span> binary matrix <\/span>grid<\/code><\/span>. An island is a group of <\/span>1<\/code><\/span>‘s (representing land) connected <\/span>4-directionally<\/span><\/strong><\/span> (horizontal or vertical.) You may assume all four edges of the grid are surrounded by water.<\/span><\/p>

The <\/span>area<\/span><\/strong><\/span> of an island is the number of cells with a value <\/span>1<\/code><\/span> in the island.<\/span><\/p>

Return <\/span>the maximum <\/span>area<\/span><\/strong> of an island in<\/span><\/em><\/span> grid<\/code><\/span>. If there is no island, return <\/span>0<\/code><\/span>.<\/span><\/p>

\u00a0<\/p>

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

\"img\"<\/span><\/p>

Input: grid = [[0,0,1,0,0,0,0,1,0,0,0,0,0],[0,0,0,0,0,0,0,1,1,1,0,0,0],[0,1,1,0,1,0,0,0,0,0,0,0,0],[0,1,0,0,1,1,0,0,1,0,1,0,0],[0,1,0,0,1,1,0,0,1,1,1,0,0],[0,0,0,0,0,0,0,0,0,0,1,0,0],[0,0,0,0,0,0,0,1,1,1,0,0,0],[0,0,0,0,0,0,0,1,1,0,0,0,0]]<\/span>
Output: 6<\/span>
Explanation: The answer is not 11, because the island must be connected 4-directionally.<\/span><\/pre>
Example 2:<\/span><\/strong><\/span><\/p>
Input: grid = [[0,0,0,0,0,0,0,0]]<\/span>
Output: 0<\/span><\/pre>
\u00a0<\/p>
Constraints:<\/span><\/strong><\/span><\/p>
  • m == grid.length<\/code><\/span><\/p><\/li>
  • n == grid[i].length<\/code><\/span><\/p><\/li>
  • 1 <= m, n <= 50<\/code><\/span><\/p><\/li>
  • grid[i][j]<\/code><\/span> is either <\/span>0<\/code><\/span> or <\/span>1<\/code><\/span>.<\/span><\/p><\/li><\/ul>\t\t\t\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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    \n\t\t\t\n\t\t\t\t\t\t<\/span>\n\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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    \u984c\u89e3\uff08DFS\uff09\uff1a<\/strong><\/span><\/h4>
    \u00a0 \u00a0 \u00a0 \u00a0\u9019\u984c\u7d66\u4e86\u6211\u5011\u4e00\u500b\u4ea4\u932f\u6578\u7d44\uff0c\u5728\u9019\u500b\u6578\u7d44\u4e2d\uff0c1\u4ee3\u8868\u9678\u5730\uff0c0\u4ee3\u8868\u6d77\u6d0b\u3002\u5982\u679c\u6709\u4e00\u7247\u9678\u5730\u4e92\u76f8\u63a5\u6518\uff08\u9678\u5730\u6578>=1\uff09\uff0c\u4e26\u88ab\u6d77\u6d0b\u6240\u5305\u570d\uff0c\u5247\u53ef\u7a31\u70ba\u4e00\u500b\u5c0f\u5cf6\u3002\u554f\u9019\u500b\u6578\u7d44\u4e2d\uff0c\u9762\u7a4d\u6700\u5927\u7684\u5cf6\u5dbc\u9762\u7a4d\u5927\u5c0f\uff0c\u4e5f\u5c31\u662f\u6578\u7d44\u4e2d\u6709\u6700\u591a\u76f8\u4e92\u9023\u63a5\u76841\u7684\u5340\u57df\u4e2d\uff0c1\u7684\u6578\u91cf\u6709\u591a\u5c11\u3002<\/p>
    \u00a0 \u00a0 \u00a0 \u00a0 \u9019\u500b\u984c\u7684\u89e3\u984c\u601d\u8def\u662f\u975e\u5e38\u5178\u578b\u7684\u6df1\u5ea6\u641c\u7d22\u3002\u5275\u5efa\u4e00\u500bisVisited\u7684bool\u985e\u578b\u4e8c\u7dad\u6578\u7d44\u6a19\u5fd7\u5df2\u7d93\u641c\u7d22\u904e\u7684\u5340\u57df\uff0c\u7136\u5f8c\u7528\u5169\u91cd\u5faa\u74b0\u4f86\u904d\u6b77\u6574\u500b\u4ea4\u932f\u6578\u7d44\uff0c\u5c0d\u6bcf\u500b\u5143\u7d20\u5617\u8a66\u9032\u884c\u6df1\u5ea6\u641c\u7d22\u3002\u5982\u679c\u7576\u524d\u884c\u5217\u7d22\u5f15\u8d85\u51fa\u908a\u754c\/\u4e0d\u662f\u9678\u5730\uff08grid[row][col] == 0\uff09\/\u5df2\u7d93\u88ab\u641c\u7d22\u904e\uff0c\u90fd\u76f4\u63a5\u8fd4\u56de\u3002\u800c\u627e\u5230\u9678\u5730\u6642\uff0c\u5247\u5c0d\u9678\u5730\u7684\u5468\u908a\u5340\u57df\u901a\u904e\u905e\u6b78\u9032\u884cDFS\uff0c\u76f4\u5230\u6aa2\u67e5\u5b8c\u6240\u6709\u76f8\u9130\u7684\u9678\u5730\uff0c\u8fd4\u56de\u8a72\u300c\u5c0f\u5cf6\u300d\u7684\u9678\u5730\u9762\u7a4d\u3002<\/p>
    \u00a0 \u00a0 \u00a0 \u00a0 \u7136\u5f8c\u5728\u5169\u5c64\u5faa\u74b0\u4e2d\u6301\u7e8c\u5229\u7528Math.Max\u4f86\u7dad\u8b77\u4e00\u500b\u300c\u6700\u5927\u9678\u5730\u9762\u7a4d\u300d\u7684\u503c\uff0c\u6700\u5f8c\u5faa\u74b0\u7d50\u675f\u5f8c\u8fd4\u56de\u7684\u503c\u5c31\u662f\u672c\u984c\u7684\u7b54\u6848\u3002<\/p>\t\t\t\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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    public<\/span> class<\/span> Solution<\/span> {<\/span>
     \u00a0 \u00a0public<\/span> int<\/span> MaxAreaOfIsland<\/span>(int<\/span>[][] grid<\/span>) {<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0int<\/span> row<\/span> =<\/span> grid<\/span>.Length<\/span>;<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0int<\/span> col<\/span> =<\/span> grid<\/span>[0<\/span>].Length<\/span>;<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0bool<\/span>[,] isVisited<\/span> =<\/span> new<\/span> bool<\/span>[row<\/span>, col<\/span>];<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0int<\/span> result<\/span> =<\/span> 0<\/span>;<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0for<\/span>(int<\/span> y<\/span> =<\/span> 0<\/span>; y<\/span> <<\/span> row<\/span>; y<\/span>++<\/span>)<\/span>
     \u00a0 \u00a0 \u00a0  {<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0for<\/span>(int<\/span> x<\/span> =<\/span> 0<\/span>; x<\/span> <<\/span> col<\/span>; x<\/span>++<\/span>)<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0 \u00a0  {<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0result<\/span> =<\/span> Math<\/span>.Max<\/span>(result<\/span>, IslandCounter<\/span>(grid<\/span>, isVisited<\/span>, y<\/span>, x<\/span>));<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0 \u00a0  }<\/span>
     \u00a0 \u00a0 \u00a0  } \u00a0 \u00a0 \u00a0 \u00a0<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0return<\/span> result<\/span>;<\/span>
     \u00a0  }<\/span>
     \u00a0 \u00a0<\/span>
     \u00a0 \u00a0int<\/span> IslandCounter<\/span>(int<\/span>[][] grid<\/span>, bool<\/span>[,] isVisited<\/span>, int<\/span> currRow<\/span>, int<\/span> currCol<\/span>)<\/span>
     \u00a0  {<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0int<\/span> rowEdge<\/span> =<\/span> grid<\/span>.Length<\/span>;<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0int<\/span> colEdge<\/span> =<\/span> grid<\/span>[0<\/span>].Length<\/span>;<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0\/\/Edge Judge<\/span><\/span>
     \u00a0 \u00a0 \u00a0 \u00a0if<\/span>(currRow<\/span> <<\/span> 0<\/span> ||<\/span> currRow<\/span> >=<\/span> rowEdge<\/span> ||<\/span> currCol<\/span> <<\/span> 0<\/span> ||<\/span> currCol<\/span> >=<\/span> colEdge<\/span>) { return<\/span> 0<\/span>; }<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0if<\/span>(grid<\/span>[currRow<\/span>][currCol<\/span>] ==<\/span> 0<\/span>) { return<\/span> 0<\/span>; }<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0\/\/isVisited Judge<\/span><\/span>
     \u00a0 \u00a0 \u00a0 \u00a0if<\/span>(isVisited<\/span>[currRow<\/span>, currCol<\/span>]) { return<\/span> 0<\/span>; }<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0\/\/Make this be visited<\/span><\/span>
     \u00a0 \u00a0 \u00a0 \u00a0isVisited<\/span>[currRow<\/span>, currCol<\/span>] =<\/span> true<\/span>;<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0\/\/DFS 4 dirs grid<\/span><\/span>
     \u00a0 \u00a0 \u00a0 \u00a0\/\/Up<\/span><\/span>
     \u00a0 \u00a0 \u00a0 \u00a0int<\/span> upCnt<\/span> =<\/span> IslandCounter<\/span>(grid<\/span>, isVisited<\/span>, currRow<\/span> -<\/span> 1<\/span>, currCol<\/span>);<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0\/\/Down<\/span><\/span>
     \u00a0 \u00a0 \u00a0 \u00a0int<\/span> downCnt<\/span> =<\/span> IslandCounter<\/span>(grid<\/span>, isVisited<\/span>, currRow<\/span> +<\/span> 1<\/span>, currCol<\/span>);<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0\/\/Left<\/span><\/span>
     \u00a0 \u00a0 \u00a0 \u00a0int<\/span> leftCnt<\/span> =<\/span> IslandCounter<\/span>(grid<\/span>, isVisited<\/span>, currRow<\/span>, currCol<\/span> -<\/span> 1<\/span>);<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0\/\/Right<\/span><\/span>
     \u00a0 \u00a0 \u00a0 \u00a0int<\/span> rightCnt<\/span> =<\/span> IslandCounter<\/span>(grid<\/span>, isVisited<\/span>, currRow<\/span>, currCol<\/span> +<\/span> 1<\/span>);<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0<\/span>
     \u00a0 \u00a0 \u00a0 \u00a0return<\/span> 1<\/span> +<\/span> upCnt<\/span> +<\/span> downCnt<\/span> +<\/span> leftCnt<\/span> +<\/span> rightCnt<\/span>;<\/span>
     \u00a0  }<\/span>
    }<\/span><\/pre>\t\t\t\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"
    \u984c\u76ee\u63cf\u8ff0\uff1a You are given an m x n binary matrix grid. An isl …<\/p>\n
      [LeetCode\u5237\u984c\u7b46\u8a18] 695 \u2013 Max Area of Island<\/span> Read More »<\/a><\/p>\n","protected":false},"author":1,"featured_media":570,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4,16],"tags":[],"class_list":["post-1699","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-programming-notes","category-leetcodes"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"https:\/\/lonelinerd.com\/wp-content\/uploads\/2021\/02\/FeatureCover_LeetCoding.png","_links":{"self":[{"href":"https:\/\/lonelinerd.com\/index.php\/wp-json\/wp\/v2\/posts\/1699","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/lonelinerd.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/lonelinerd.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/lonelinerd.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/lonelinerd.com\/index.php\/wp-json\/wp\/v2\/comments?post=1699"}],"version-history":[{"count":17,"href":"https:\/\/lonelinerd.com\/index.php\/wp-json\/wp\/v2\/posts\/1699\/revisions"}],"predecessor-version":[{"id":1717,"href":"https:\/\/lonelinerd.com\/index.php\/wp-json\/wp\/v2\/posts\/1699\/revisions\/1717"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/lonelinerd.com\/index.php\/wp-json\/wp\/v2\/media\/570"}],"wp:attachment":[{"href":"https:\/\/lonelinerd.com\/index.php\/wp-json\/wp\/v2\/media?parent=1699"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/lonelinerd.com\/index.php\/wp-json\/wp\/v2\/categories?post=1699"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/lonelinerd.com\/index.php\/wp-json\/wp\/v2\/tags?post=1699"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}