java—稀疏数组

当一个数组存在大量0或同一数值时，可以通过稀疏数组保存原数组

        int [][] a = new int[11][11];
        a[1][2] = 1;
        a[2][3] = 2;
        //输出原始数组
        System.out.println("原始数组");
        for(int[] ints : a) {
            for (int anInt : ints) {
                System.out.print(anInt + "t");
            }
            System.out.println();
        }

//获取有效值个数
        int sum = 0;
        for (int i = 0; i < 11; i++) {
            for (int j = 0; j < 11; j++) {
                if (a[i][j] != 0)
                    sum++;
            }
        }
        //创建一个稀疏数组
        int[][] b = new int[sum+1][3];
        b[0][0] = 11;
        b[0][1] = 11;
        b[0][2] = sum;
        //将非零的值存放稀疏数组中
        int count = 0;
        for (int i = 0; i < a.length; i++) {
            for (int j = 0; j < a[i].length; j++) {
                if (a[i][j] != 0) {
                    count++;
                    b[count][0] = i;
                    b[count][1] = j;
                    b[count][2] = a[i][j];
                }
            }
        }
        //打印稀疏数组
        System.out.println("稀疏数组");
        for (int i = 0; i < b.length; i++) {
            System.out.println(b[i][0] + " " + b[i][1] + " " + b[i][2] + " " );

        }

//读取稀疏数组
        int[][] c = new int[b[0][0]][b[0][1]];

        //还原
        for (int i = 1; i < b.length; i++) {
            c[b[i][0]][b[i][1]] = b[i][2];
        }

        //输出
        System.out.println("输出原数组");
        for (int[] ints : c) {
            for (int anInt : ints) {
                System.out.print(anInt + "t");
            }
            System.out.println();
        }