You can transverse the diagonal to map where each block starts and ends.
The transverse can be done by dfs or simple loop.
Then key is detecting a block end. With "full" blocks is is quiet simple as demonstrated in isCorner method.
This method will have to be modified to account for holes.
//test data
public static int[][] intArray = {
{1, 1, 0, 0, 0, 0, 0, 0, 0},
{1, 1, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 1, 1, 1, 1, 0, 0, 0},
{0, 0, 1, 1, 1, 1, 0, 0, 0},
{0, 0, 1, 1, 1, 1, 0, 0, 0},
{0, 0, 1, 1, 1, 1, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 1, 1, 1},
{0, 0, 0, 0, 0, 0, 1, 1, 1},
{0, 0, 0, 0, 0, 0, 1, 1, 1}
};
public static void main(String[] args) {
mapBlock();
}
//traverse diagonal to find block start and block end
private static void mapBlock() {
//todo check that matrix is nxn
int[] origin = {0,0}; //dfs start point
//traverse diagonal
for(int rowIndex =0; rowIndex < intArray.length ; rowIndex ++) {
if(isCorner(rowIndex, rowIndex)) { //diagonal row and col index are equal
int[] target = {rowIndex, rowIndex}; //dfs target
block(origin, target);
origin = new int[]{rowIndex+1, rowIndex+1};
}
}
}
//is intArray[row Index][column Index] a corner
private static boolean isCorner(int rowIndex, int colIndex) {
//corner must be on diagonal
if(rowIndex != colIndex ) {
return false;
}
//if last row and col it is a corner
if(((rowIndex+1) == intArray.length) && ((colIndex+1) == intArray.length)) {
return true;
}
//if left and bottom neighbors are empty - it is a corner
//todo if you blocks have holes this criteria needs to change
if((intArray[rowIndex+1][colIndex] == 0) && (intArray[rowIndex][colIndex+1] == 0) ) {
return true;
}
return false;
}
private static void block(int[] origin, int[] target) {
System.out.println("block from " +Arrays.toString(origin)+
" to "+Arrays.toString(target));
//todo store sub array
}
Output:
block from [0, 0] to [1, 1]
block from [2, 2] to [5, 5]
block from [6, 6] to [8, 8]
(Test it online )
