Rotting Oranges

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In this tutorial, i am going to discuss a very interesting problem rotting oranges (minimum time required to rot all fresh oranges).

Given an m*n grid where each cell in the matrix can have values 0, 1 or 2.

0 represents an empty cell
1 represents cells have fresh oranges
2 represents cells have rotten oranges

Every minute, any fresh orange that is 4-directionally adjacent to a rotten orange becomes rotten.

Return the minimum number of minutes that must elapse until no cell has a fresh orange. If this is impossible, return -1.

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Range Sum of BST

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Let’s discuss a problem range sum of BST (binary search tree).

In this problem, given the root node of a binary search tree and two integers low and high, return the sum of values of all nodes with a value in the inclusive range [low, high].

Binary Search Tree (BST)

In binary search tree, the value of all the nodes in the left sub-tree is less than the value of the root node. Similarly, Value of all the nodes in the right sub-tree is greater than or equal to the value of the root.

For example

In the below example (image), we have to find the sum of all nodes whose value lies in the range of 7 to 15 (inclusive).

The nodes 7, 10, and 15 lie in this range and its sum is 32.

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