LiteCode-Search Range in Binary Search Tree

Description

Given a binary search tree and a range [k1, k2], return all elements in the given range.

Example

If k1 = 10 and k2 = 22, then your function should return [12, 20, 22].

    20
   /  \
  8   22
 / \
4   12

• 题目模板

  /**
  * Definition of TreeNode:
  * class TreeNode {
  * public:
  *     int val;
  *     TreeNode *left, *right;
  *     TreeNode(int val) {
  *         this->val = val;
  *         this->left = this->right = NULL;
  *     }
  * }
  */
  
  class Solution {
  public:
    /**
     * @param root: param root: The root of the binary search tree
     * @param k1: An integer
     * @param k2: An integer
     * @return: return: Return all keys that k1<=key<=k2 in ascending order
     */
    vector<int> searchRange(TreeNode * root, int k1, int k2) {
        // write your code here
    }
  };
  

• 题目大意

  给你一个二叉搜索树，和两个数k1，k2，让你输出在数中值介于这两个数的数。

• 大概思路

  没啥好说的，遍历书吧，深搜广搜都可以。

  /**
  * Definition of TreeNode:
  * class TreeNode {
  * public:
  *     int val;
  *     TreeNode *left, *right;
  *     TreeNode(int val) {
  *         this->val = val;
  *         this->left = this->right = NULL;
  *     }
  * }
  */
  
  class Solution {
  public:
    /**
     * @param root: param root: The root of the binary search tree
     * @param k1: An integer
     * @param k2: An integer
     * @return: return: Return all keys that k1<=key<=k2 in ascending order
     */
    vector<int> searchRange(TreeNode * root, int k1, int k2) {
        // write your code here
        queue<TreeNode*> q;
        vector<int> v;
        if(!root)
          return v;
  
        q.push(root);
        while(!q.empty()){
          TreeNode *t = q.front();
          q.pop();
          if(t->val >= k1 && t->val <= k2)
            v.push_back(t->val);
          if(t->left)
            q.push(t->left);
          if(t->right)
            q.push(t->right);
        }
        return v;
    }
  };
  

• 细节方面

  注意树可能为空直接返回空vector就可以了。

• 题目链接: https://www.lintcode.com/problem/search-range-in-binary-search-tree/description