Number of Islands 2
Question
Given a n,m which means the row and column of the 2D matrix and an array of pair A( size k). Originally, the 2D matrix is all 0 which means there is only sea in the matrix. The list pair has k operator and each operator has two integer A[i].x, A[i].y means that you can change the grid matrix[A[i].x][A[i].y] from sea to island. Return how many island are there in the matrix after each operator.
Example
Given n = 3, m = 3, array of pair A = [(0,0),(0,1),(2,2),(2,1)].
return [1,1,2,2].
Note 0 is represented as the sea, 1 is represented as the island. If two 1 is adjacent, we consider them in the same island. We only consider up/down/left/right adjacent.
Analysis
感觉要用并查集(unionfind)做比较好