807. Max Increase to Keep City Skyline

There is a city composed of n x n blocks, where each block contains a single building shaped like a vertical square prism. You are given a 0-indexed n x n integer matrix grid where grid[r][c] represents the height of the building located in the block at row r and column c. A city's skyline is the outer contour formed by all the building when viewing the side of the city from a distance. The skyli