如何通过保存最大元素值来减少矩阵？

Question

假设我有一个矩阵

int[][] matrix = {
        // 0     1     2
        {0,0,  0,0,  0,0}, // 0
        {0,1,  0,0,  0,0},

        {1,1,  0,0,  0,0}, // 1
        {0,0,  0,0,  0,1} 
};

int newCellSize = 2;

我希望通过保持单元格的最大值来减少它。例如，

matrix =＆gt;

int[][] reducedMatrix = {
        {1, 0, 0},
        {1, 0, 1}
};

我该怎么做？如何遍历matrix元素并将它们映射到reducedMatrix单元格？

这是我的尝试：

private static int[][] reduceMatrix(int[][] matrix, int cellSize) {

    int a = (int)ceil((double)matrix.length/cellSize);
    int b = (int)ceil((double)matrix[0].length/cellSize);

    int[][] reduced = new int[a][b];

    for(int i=0; i < matrix.length; i++){
        for(int j=0; j < matrix[i].length; j++){

            int n= i / cellSize;
            int m= j / cellSize;

            int elem = matrix[i][j];

            if(elem > 0){
                reduced[n > 0 ? n : 0][m > 0 ? m : 0]=elem;
            }
        }
    }

    return reduced;
}

Answer 1

这段代码应该可以解决问题：

int[][] reduceMatrix(int[][] matrix, int cellSize, int rows, int cols) {
    int [][] reducedMatrix = new int[rows/cellSize][cols/cellSize];
    for (int i=0; i<rows; i+=cellSize) {
        for (int j=0; j<cols; j+=cellSize) {
            int max=-INF;
            for (k=i;k<cellSize;k++)
                for (l=j;l<cellSize;l++)
                    if (matrix[k][l]>max)
                        max=matrix[k][l];
            reducedMatrix[i/cellSize][j/cellSize] = max;
        }
    }
    return reducedMatrix;
}