Algo - matrix

Question 1

2132. Stamping the Grid
2133. given a matrix with 0 is empty, 1 is blocked
2134. given an infinite number of stamps of width and height
2135. check if can cover all empty with stamps
      Notices:
2136. stamp must stay within the grid
2137. stamps can be overlapped by other
2138. stamp cannot cover blocked cell

Answer 1

1. prefixSums: to sum sub-matrix => know if can put a stamp at current cell or not. If yes, put a stamp there. Note: must check range of cornerRow, cornerCol
2. prefixSumStamps: to sum sub-matrix of cell with stamps
3. using prefixSumStamps to check each cell if has already been covered