Upgrade every day

Summarize the record of personal effort deduction and question brushing ：

STL Comprehensive application of containers https://leetcode.cn/problems/cong-shang-dao-xia-da-yin-er-cha-shu-iii-lcof/submissions/ Code ：

  class Solution 
  {
  public:
      vector<vector<int>> levelOrder(TreeNode* root)
      {
          vector<vector<int>>res_vec;// Container for storing results 
          if (!root)
          {
              return res_vec;
          }
          queue< TreeNode*>T_que; // Use the special line of the queue to store the nodes of the tree 
          T_que.push(root);
          bool Inleft = true; // Determine a condition that requires traversing the left tree 
          while (!T_que.empty()) // As long as there are elements in the container, it keeps cycling 
          {
              int len = T_que.size(); // Get the number of elements in the queue 
              deque<int>D_que;// Use the special effect of double ended array to traverse the left and right trees 
              for (int i = 0; i < len; ++i)
              {
                  TreeNode* temp = T_que.front(); // Get the team head element and leave the team 
                  T_que.pop();
                  if (Inleft)// First, judge the left and right trees according to the requirements of the topic 
                  {
                      D_que.push_back(temp->val); // If it's in the left tree, then insert the head 
                  }
                  else
                  {
                      D_que.push_front(temp->val); // conversely 
                  }
                  if (temp->left) T_que.push(temp->left);
                  if (temp->right) T_que.push(temp->right);
              }
              res_vec.emplace_back(vector<int>{D_que.begin(), D_que.end()});
              Inleft = !Inleft;
          }
          return res_vec;
      }
  };

Execution results ：

  This question mainly considers using three STL Container solution , Can deepen right STL The understanding of the , I believe I can finish this problem , Yes STL Your mastery will be slightly improved

Hashtable ：141 Circular list

The greatest value of gifts https://leetcode.cn/problems/li-wu-de-zui-da-jie-zhi-lcof/

I think this question is a great test of logical ability

Answer key ：

  class Solution {
  public:
      int maxValue(vector<vector<int>>& grid)
      {
          int hang = grid.size();
          int lie = grid[0].size();
          vector<vector<int>>dp(hang, vector<int>(lie, 0));
          dp[0][0] = grid[0][0];
          for (int j = 1; j < lie; ++j) dp[0][j] = dp[0][j - 1] + grid[0][j];
          for (int i = 1; i < hang; ++i) dp[i][0] = dp[i - 1][0] + grid[i][0];       
          for (int z = 1; z < hang; ++z)
          {
              for (int x = 1; x < lie; ++x)
              {
                  dp[z][x] = max(dp[z][x - 1], dp[z - 1][x]) + grid[z][x];
              }
          }
          return dp[hang - 1][lie - 1];
      }
  };

Execution results ：