{"id":192781,"date":"2020-11-15T08:51:51","date_gmt":"2020-11-15T00:51:51","guid":{"rendered":"http:\/\/4563.org\/?p=192781"},"modified":"2020-11-15T08:51:51","modified_gmt":"2020-11-15T00:51:51","slug":"google-%e9%9d%a2%e8%af%95%e9%a2%98%ef%bc%9a-k-%e6%95%b0%e4%b9%8b%e5%92%8c","status":"publish","type":"post","link":"http:\/\/4563.org\/?p=192781","title":{"rendered":"Google \u9762\u8bd5\u9898\uff1a K \u6570\u4e4b\u548c"},"content":{"rendered":"
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Google \u9762\u8bd5\u9898\uff1a K \u6570\u4e4b\u548c <\/h1>\n

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\u8cc7\u6df1\u5927\u4f6c : zzzrf <\/span> <\/i> 0<\/span> <\/div>\n
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\u7ed9\u5b9a n \u4e2a\u4e0d\u540c\u7684\u6b63\u6574\u6570\uff0c\u6574\u6570 k \uff08 k <= n \uff09\u4ee5\u53ca\u4e00\u4e2a\u76ee\u6807\u6570\u5b57 target \u3002\u3000 \u5728\u8fd9 n \u4e2a\u6570\u91cc\u9762\u627e\u51fa k \u4e2a\u6570\uff0c\u4f7f\u5f97\u8fd9 k \u4e2a\u6570\u7684\u548c\u7b49\u4e8e\u76ee\u6807\u6570\u5b57\uff0c\u6c42\u95ee\u6709\u591a\u5c11\u79cd\u65b9\u6848\uff1f<\/p>\n

\u6837\u4f8b 1<\/h2>\n
\u8f93\u5165: List = [1,2,3,4] k = 2 target = 5 \u8f93\u51fa: 2 \u8bf4\u660e: 1 + 4 = 2 + 3 = 5 <\/code><\/pre>\n
\u6837\u4f8b 2<\/h2>\n
\u8f93\u5165: List = [1,2,3,4,5] k = 3 target = 6 \u8f93\u51fa: 1 \u8bf4\u660e: \u53ea\u6709\u8fd9\u4e00\u79cd\u65b9\u6848\u30021 + 2 + 3 = 6 <\/code><\/pre>\n
\u7b97\u6cd5\uff1adp<\/h2>\n
\u5982\u679c\u6ca1\u6709 k \u7684\u7ea6\u675f\u3002\u6211\u4eec\u53ef\u4ee5\u53d1\u73b0\uff0c\u8fd9\u9898\u5c31\u53ef\u4ee5\u8f6c\u5316\u4e3a\u80cc\u5305\u95ee\u9898\u3002\u5229\u7528 n \u4e2a\u6b63\u6574\u6570\u8fbe\u5230\u76ee\u6807 target \u3002\u90a3\u4e48\u6709\u4e86 k \u7684\u7ea6\u675f\u4e4b\u540e\uff0c\u6211\u4eec\u9700\u8981\u7528\u989d\u5916\u7684\u4e00\u7ef4\u6765\u7ef4\u62a4\u4f7f\u7528\u7684\u6570\u5b57\u3002\u6240\u4ee5\u7ea6\u5b9a\u72b6\u6001\u5982\u4e0b\uff0c\u7528 dp[i][j][k]\u8868\u793a\u524d ii \u4e2a\u6570\u91cc\u9009 j \u4e2a\u548c\u4e3a k \u7684\u65b9\u6848\u6570\u3002<\/p>\n
    \n
  • \u5047\u5b9a dp[i][j][k]\u4e4b\u524d\u7684\u65b9\u6848\u6570\u90fd\u5df2\u77e5\uff0c\u8003\u8651 dp[i][j][k]\u7684\u60c5\u51b5\u3002<\/li>\n
  • dp[i][j][k]\u53ef\u4ee5\u7531 dp[i\u22121][j\u22121][k\u2212A[i\u22121]]\u7684\u72b6\u6001\u53d6 A[i-1]\u5f97\u5230\u3002<\/li>\n
  • dp[i][j][k]\u4e5f\u53ef\u4ee5\u7531 dp[i\u22121][j][k]\u76f4\u63a5\u5f97\u5230\uff0c\u5373\u4e0d\u53d6 A[i-1]\u3002<\/li>\n
  • \u6700\u540e\u8fd4\u56de f[n][k][target]\u5373\u53ef\u3002<\/li>\n<\/ul>\n
    \u590d\u6742\u5ea6\u5206\u6790<\/h2>\n
      \n
    • \u65f6\u95f4\u590d\u6742\u5ea6 O(n\u2217k\u2217target)O(n\u2217k\u2217target)<\/li>\n
    • \u7a7a\u95f4\u590d\u6742\u5ea6 O(n\u2217k\u2217target)O(n\u2217k\u2217target)\n
        \n
      • \u65f6\u95f4\u590d\u6742\u5ea6\u4e0e\u7a7a\u95f4\u590d\u6742\u5ea6\u662f\u7b49\u4ef7\u7684\u3002<\/li>\n
      • \u5728\u8fd9\u91cc\uff0c\u7a7a\u95f4\u590d\u6742\u5ea6\u53ef\u4ee5\u7528\u6eda\u52a8\u6570\u7ec4\u4f18\u5316\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
        public class Solution {     \/**      * @param A: an integer array.      * @param k: a positive integer (k <= length(A))      * @param target: a integer      * @return an integer      *\/     public int  kSum(int A[], int k, int target) {         int n = A.length;         int[][][] f = new int[n + 1][k + 1][target + 1];         for (int i = 0; i < n + 1; i++) {             f[i][0][0] = 1;         }         for (int i = 1; i <= n; i++) {             for (int j = 1; j <= k && j <= i; j++) {                 for (int t = 1; t <= target; t++) {                     f[i][j][t] = 0;                     if (t >= A[i - 1]) {                         f[i][j][t] = f[i - 1][j - 1][t - A[i - 1]];                     }                     f[i][j][t] += f[i - 1][j][t];                 } \/\/ for t             } \/\/ for j         } \/\/ for i         return f[n][k][target];     } } <\/code><\/pre>\n<\/p><\/div>\n
         \u5927\u4f6c\u6709\u8a71\u8aaa<\/b> (3<\/span>)        <\/div>\n
         <\/div>\n<\/p><\/div>\n<\/p><\/div>\n
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        • \n
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           \u8cc7\u6df1\u5927\u4f6c : b1ackjack <\/span>  <\/div>\n
           <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                       \u6211\u600e\u4e48\u89c9\u5f97\u50cf dfs                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
        • \n
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           \u8cc7\u6df1\u5927\u4f6c : yuruizhe <\/span>  <\/div>\n
           <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                       @b1ackjack \u7edd\u903c\u8d85\u65f6\uff0c\u60f3\u90fd\u522b\u60f3                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
        • \n
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           \u8cc7\u6df1\u5927\u4f6c : lewis89 <\/span>  <\/div>\n
           <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                       @yuruizhe #2 
          @b1ackjack #1 <\/p>\n
          \u4e00\u822c\u8fd9\u79cd\u641c\u7d22\u6811\u7684\u9898 \u672c\u6765\u5c31\u662f\u8981\u8ba9\u4f60 dfs \u8d85\u65f6\u7684\uff0c
          \u56e0\u4e3a n \u4f1a\u8bbe\u7f6e\u5f88\u5927\uff0c\u4e0d\u4f1a\u8ba9\u4f60 dfs \u66b4\u529b\u641c\u7d22\u7684\uff0c\u66b4\u529b\u641c\u7d22\u4f1a\u6709\u5f88\u591a\u91cd\u590d\u8ba1\u7b97\u3002<\/p>\n
          \u57fa\u672c\u5957\u8def\u662f \u751f\u6210\u6811\uff0c\u641c\u7d22\uff0c\u641c\u7d22\u7edd\u5bf9\u8d85\u65f6\uff0c\u7136\u540e\u6253\u8868\u526a\u679d\u3002<\/p>\n
          \u7136\u540e\u8fdb\u4e00\u6b65\u4f18\u5316\u5c31\u662f dp\uff0c\u7528\u5df2\u7ecf\u751f\u6210\u7684\u7ed3\u679c\u53bb\u9012\u63a8\u540e\u9762\u7684\u8fd0\u7b97\u3002<\/p>\n
          dp \u96be\u5728\u9012\u63a8\u516c\u5f0f\u7684\u63a8\u5bfc\uff0c\u7f16\u7a0b\u5012\u662f\u6b21\u8981\u7684\uff0cdp \u63a8\u5bfc\u662f\u4e00\u4e2a\u70e7\u8111\u5b50\u7684\u4e8b\u60c5\uff0c\u8981\u6709\u8db3\u591f\u7684\u5206\u6790\u80fd\u529b\u624d\u80fd\u63a8\u5bfc\u51fa\u6765\uff0c
          \u4f46\u662f\u5bf9\u4e8e\u5927\u90e8\u5206\u8fd9\u79cd\u7c7b\u4f3c\u7684\u573a\u666f\uff0cN \u4e0d\u5927\u7684\u60c5\u51b5\uff0c\u4f7f\u7528\u66b4\u529b\u641c\u7d22\u662f\u6700\u6709\u6548\uff0c\u4e5f\u662f\u6700\u5bb9\u6613\u7ef4\u62a4\u5b9e\u73b0\u7684\uff0c\u4e0d\u8fc7\u5948\u4f55
          \u7a0b\u5e8f\u5458\u5f97\u4eba\u4eba\u4f1a DP                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
        • \n","protected":false},"excerpt":{"rendered":"
          Google \u9762\u8bd5\u9898\uff1a K \u6570\u4e4b\u548c…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[],"tags":[],"_links":{"self":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/192781"}],"collection":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=192781"}],"version-history":[{"count":0,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/192781\/revisions"}],"wp:attachment":[{"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=192781"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=192781"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=192781"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}