Calculate sum of root to leaf digits in a binary tree
Given a binary tree, where each node stores a value between 0 and 9, calculate the sum of the numbers created by the paths from root to leaf.
Category: Queue
Construct a complete binary tree from its linked list representation
Given a linked list, construct a complete binary tree from it. Assume that the order of elements present in the linked list is the same as that in the complete tree’s array representation.
Find the minimum depth of a binary tree
Given a binary tree, find its minimum depth. The minimum depth is the total number of nodes along the shortest path from the root node down to the nearest leaf node.
Invert alternate levels of a perfect binary tree
Write an efficient algorithm to invert alternate levels of a perfect binary tree.
Convert a Binary Search Tree into a Min Heap
Given a binary search tree (BST), efficiently convert it into a min-heap. In order words, convert a binary search tree into a complete binary tree where each node has a higher value than its parent’s value.
Convert a binary tree into a doubly-linked list in spiral order
Given a binary tree, convert it into a doubly-linked list following the spiral order.
Find minimum passes required to convert all negative values in a matrix
Given an M × N matrix of integers whose each cell can contain a negative, zero, or a positive value, determine the minimum number of passes required to convert all negative values in the matrix positive.
Check if a binary tree is a min-heap or not
Given a binary tree, check if it is a min-heap or not. In order words, the binary tree must be a complete binary tree where each node has a higher value than its parent’s value.
Construct a directed graph from an undirected graph that satisfies given constraints
Given a connected undirected graph and a vertex in the graph, construct a directed graph such that any path in the directed graph leads to that particular vertex.
Implement a stack using the queue data structure
This post will implement a stack using the queue data structure. In other words, design a stack that supports push and pop operations using standard enqueue and dequeue operations of the queue.
Depth-First Search (DFS) vs Breadth-First Search (BFS)
This post will cover the difference between the Depth–first search (DFS) and Breadth–first search (BFS) algorithm used to traverse/search tree or graph data structure.
Efficiently print all nodes between two given levels in a binary tree
Given a binary tree, efficiently print all nodes between two given levels in a binary tree. The nodes for any level should be printed from left to right.