C++ BFS Algorithm for Minimum Water Drops to Water Trees in a Garden

The given code is a solution to a problem where there is a garden represented by a 2D grid. Each cell in the grid can be either empty ('.') or contain a tree ('#') or a water drop ('*'). The goal is to count the minimum number of water drops required to water all the trees in the garden.

The code uses a breadth-first search (BFS) algorithm to find the connected component of trees for each water drop. It starts by iterating through each cell in the grid and if it finds a water drop that is not visited, it performs a BFS to find the connected component of trees. The BFS starts from the current water drop cell and explores all the neighboring cells that are valid (not visited and not containing a tree or water drop). It counts the number of cells visited during the BFS and returns it as the number of water drops required for that connected component.

The main function reads the input grid size (n x m) from the user and creates the garden and visited vectors accordingly. Then, it reads the grid elements from the user. After that, it iterates through each cell in the grid and if it finds a water drop that is not visited, it calls the BFS function and adds the result to the minimum number of drops variable.

Finally, it prints the minimum number of drops required to water all the trees in the garden.

Overall, the code efficiently solves the problem using BFS and provides the expected output.