Number of Islands with Incremental Land Additions

Number of Islands with Incremental Land Additions Given an m x n grid of '0' (water) and '1' (land), horizontally or vertically adjacent land cells belong to the same island. Implement numIslands(grid) to return the number of islands. Follow-up: the grid initially contains only water. Given a sequence of land positions to add, return the island count after each addition. If a position is added more than once, the island count remains unchanged for that operation. Example m = 3, n = 3 positions = [[0,0], [0,1], [1,2], [2,1]] Output: [1, 1, 2, 3] Constraints 1 <= m, n <= 10^4 Number of additions k <= 10^5 Do not rescan the whole grid after every addition. Example Input 3 3 4 0 0 0 1 1 2 2 1 Output 1 1 2 3