java-稀疏矩阵简单范例

/**
 * 稀疏矩阵算法
 */
public class SparseMatrix {

    /**
     * 矩阵转稀疏矩阵
     * @param arr
     * @return
     */
    public static int[][] arrToSparse(int[][] arr){
        int cl = 1;
        for (int i = 0; i < arr.length; i++) {
            for (int j = 0; j < arr[i].length; j++) {
                if(arr[i][j] != 0){
                    cl++;
                }
            }
        }
        int[][] sarr = new int[cl][3];
        sarr[0][0] = arr.length;
        sarr[0][1] = arr[0].length;
        sarr[0][2] = cl - 1;
        int count = 1;
        for (int i = 0; i <arr.length ; i++) {
            for (int j = 0; j < arr[i].length; j++) {
                if(arr[i][j] != 0){
                    sarr[count][0] = i;
                    sarr[count][1] = j;
                    sarr[count][2] = arr[i][j];
                    count++;
                }
            }
        }

        return sarr;
    }

    /**
     * 稀疏矩阵转完整矩阵
     * @param arr
     * @return
     */
    public static int[][] sparseToArr(int[][] arr){
        int[][] rarr = new int[arr[0][0]][arr[0][1]];
        for (int i = 1; i <= arr[0][2]; i++) {
            rarr[arr[i][0]][arr[i][1]] = arr[i][2];
        }

        return rarr;
    }

    public static void main(String[] args) {
        int[][] arr = new int[11][11];
        arr[1][2] = 1;
        arr[2][3] = 2;
        for (int i = 0; i < arr.length; i++) {
            for (int j = 0; j < arr[i].length; j++) {
                System.out.printf("%d \t",arr[i][j]);
            }
            System.out.printf("\n");
        }
        //转
        int[][] sarr = arrToSparse(arr);
        for (int i = 0; i < sarr.length; i++) {
            for (int j = 0; j < sarr[i].length; j++) {
                System.out.printf("%d \t",sarr[i][j]);
            }
            System.out.printf("\n");
        }
        //返
        int[][] rarr = sparseToArr(sarr);
        for (int i = 0; i < rarr.length; i++) {
            for (int j = 0; j < rarr[i].length; j++) {
                System.out.printf("%d \t",rarr[i][j]);
            }
            System.out.printf("\n");
        }
    }
}