# 807. Max Increase to Keep City Skyline """ there is a city composed of 'n * n' blocks where each block contains a single building shaped like a vertical square prisum. you are given 0 idxed 'n * 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 skiline is the outer contour formed by all the building =hen viewing the side of the city from a distance. the skyline from a distance. the skyline from each cardinal direction, north, east, south, and west may be different. we are allowed to increase the height of any number of buildings by any amount. the height of a 0-height building can also be increased. however, increasing the height of a building should not affect the city's skyline from any cardinal direction. return the maximum total sum that the height of the buildings can be increased by without changing the city's skyline from any cardinal direction """ class Solution(object): def maxIncreaseKeepingSkyline(self, grid): """ :type grid: List[List[int]] :rtype: int """ sum = 0 l1 = [max(i) for i in zip(*grid)] l2 = [max(i) for i in grid] for i in range(len(grid)): for j in range(len(grid)): sum += min(l1[j], l2[i]) - grid[i][j] return sum if __name__ == "__main__": obj = Solution() print( obj.maxIncreaseKeepingSkyline( grid=[[3, 0, 8, 4], [2, 4, 5, 7], [9, 2, 6, 3], [0, 3, 1, 0]] ) ) print(obj.maxIncreaseKeepingSkyline(grid=[[0, 0, 0], [0, 0, 0], [0, 0, 0]]))