1130. 叶值的最小代价生成树

Posted 2021-03-25 zouma

1.dp

 1 int mctFromLeafValues(vector<int>& arr) {
 2     int len = arr.size();
 3     vector<vector<int>> rmq(len, vector<int>(len, 0));
 4     for (int i = 0; i < len; i++)
 5         rmq[i][0] = arr[i];
 6     for (int j = 1;  (1<<j)<len ; j++)
 7     {
 8         for (int i = 0;  i+(1<<j-1)<len ; i++)
 9         {
10             rmq[i][j] = max(rmq[i][j - 1], rmq[i + (1 << j - 1)][j - 1]);
11         }
12     }
13     vector<vector<int>> dp(len, vector<int>(len, INT_MAX));
14     for (int i = 0; i < len; i++)
15         dp[i][i] = 0;
16     for (int i = 1; i < len; i++)
17     {
18         for (int j = 0; j < len - i; j++)
19         {
20             for (int k = j; k < i + j; k++)
21             {
22                 int width1 = log2(k - j + 1);
23                 int width2 = log2(j + i - k);
24                 dp[j][j + i] = min(dp[j][j + i], dp[j][k] + dp[k + 1][j + i] + max(rmq[j][width1],rmq[k-(1<<width1)+1][width1])*max(rmq[k+1][width2],rmq[j+i-(1<<width2)+1][width2]));
25             }
26         }
27     }
28     return dp[0][len - 1];
29 }