973. K Closest Points to Origin
Medium : https://leetcode.com/problems/k-closest-points-to-origin/solution/
We have a list of points on the plane. Find the K closest points to the origin (0, 0).
(Here, the distance between two points on a plane is the Euclidean distance.)
You may return the answer in any order. The…
https://leetcode.com/problems/repeated-substring-pattern/
Easy But tough for me as I do not know two of the algorithms
Given a non-empty string check if it can be constructed by taking a substring of it and appending multiple copies of the substring together. …
Medium — Leetcode: https://leetcode.com/problems/decoded-string-at-index/solution/
An encoded string S is given. To find and write the decoded string to a tape, the encoded string is read one character at a time and the following steps are taken:
Medium(https://leetcode.com/problems/populating-next-right-pointers-in-each-node/submissions/)
You are given a perfect binary tree where all leaves are on the same level, and every parent has two children. The binary tree has the following definition:
struct Node {
int val;
Node *left;
Node *right;
Node *next;
}Populate each next pointer to point to its next…
Medium : https://leetcode.com/problems/binary-tree-right-side-view/
Given a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom.
Example:
Input: [1,2,3,null,5,null,4]
Output: [1, 3, 4]
Explanation: 1 <---
/ \
2 3 <---
\ \
5 4 <---
…
Iterative — Easy : https://leetcode.com/problems/symmetric-tree/
Recursive — Medium [ very important and intuitive]
Hint : 1. A Tree is symmetric to itself. So if you implement a function which accepts two trees to check for symmetry, you can start the first call of the function with symmetric(root, root).
Problem Statement:
…
Easy
Sum of Left Leaves
Easy : https://leetcode.com/problems/sum-of-left-leaves/
Find the sum of all left leaves in a given binary tree.
Example:
3
/ \
9 20
/ \
15 7There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24.
Iterative Code:
#…Medium- Hard, https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal/solution/
Given a binary tree, return the zigzag level order traversal of its nodes’ values. (ie, from left to right, then right to left for the next level and alternate between).
During interview:
Following the previous post on BF traversal of BSTrees, here is another cool problem often can be easily described using two different data structures. A dictionary and a Tree at play. Please read along ..
Top view of a binary tree is the set of nodes visible when the tree…
In this post, I will summarize a Binary’s Search Trees (BST)s, level order traversal. I picked this problem from HackerRank Site and feel like, its been touch based so much every where it needs a place where the problem and solution can be easily searched and read. …
