zoukankan      html  css  js  c++  java
  • LC 987. Vertical Order Traversal of a Binary Tree

    Given a binary tree, return the vertical order traversal of its nodes values.

    For each node at position (X, Y), its left and right children respectively will be at positions (X-1, Y-1) and (X+1, Y-1).

    Running a vertical line from X = -infinity to X = +infinity, whenever the vertical line touches some nodes, we report the values of the nodes in order from top to bottom (decreasing Y coordinates).

    If two nodes have the same position, then the value of the node that is reported first is the value that is smaller.

    Return an list of non-empty reports in order of X coordinate.  Every report will have a list of values of nodes.

    class Solution {
    public:
      vector<vector<int>> verticalTraversal(TreeNode* root) {
        map<int,map<int,vector<int>>> mp;
        vector<vector<int>> ret;
        helper(root, 0, 0, mp);
        for(auto it=mp.begin(); it!=mp.end(); it++){
          vector<int> a;
          for(auto iit=it->second.rbegin(); iit!=it->second.rend(); iit++) {
            vector<int> tmp = iit->second;
            sort(tmp.begin(), tmp.end());
            for(auto x : tmp) a.push_back(x);
          }
          ret.push_back(a);
        }
        return ret;
      }
      void helper(TreeNode* root,int x,int y, map<int,map<int,vector<int>>>& mp){
        if(!root) return;
        mp[x][y].push_back(root->val);
        helper(root->left, x-1, y-1, mp);
        helper(root->right, x+1, y-1, mp);
      }
    };
  • 相关阅读:
    全排列
    RazorPages中的绑定
    SQL Server安装步骤
    2020-2021---开发工作总述
    C#.NET编程的特点
    VS自带Git的使用
    从apk反编译出.java文件
    基于页面的编程模型+关于设计的表达
    XtraReport注意事项
    Android总结
  • 原文地址:https://www.cnblogs.com/ethanhong/p/10350073.html
Copyright © 2011-2022 走看看