稀疏数组

压缩

记录原数组有效数据原始坐标及有效值

利用坐标还原数组

package array;

public class SparseArray {
   public static void main(String[] args) {
       int[][] array1 = new int[11][11];
       array1[1][2] = 1;
       array1[2][3] = 2;
       array1[10][8] = 4;
       //before
       for (int[] ints : array1) {
           for (int anInt : ints) {
               System.out.print(anInt + "\t");
          }
           System.out.println();
      }
       //sparse
       int sum = 0;
       for (int i = 0; i < 11; i++) {
           for (int j = 0; j < 11; j++) {
               if (array1[i][j] != 0) {
                   sum++;
              }
          }
      }
       System.out.println(sum);
       System.out.println("=============");
       int[][] array2 = new int[sum + 1][3];
       int count = 0;
       array2[0][0] = 11;
       array2[0][1] = 11;
       array2[0][2] = sum;
       for (int i = 0; i < array1.length; i++) {
           for (int j = 0; j < array1[i].length; j++) {
               if (array1[i][j] != 0) {
                   count++;
                   array2[count][0] = i;
                   array2[count][1] = j;
                   array2[count][2] = array1[i][j];
              }
          }
      }
       System.out.println("row\tcol\tvalue");
       for (int i = 0; i < array2.length; i++) {
           System.out.println(array2[i][0] + "\t" + array2[i][1] + "\t" + array2[i][2]);
      }
       System.out.println("=============");
       //revivification
       int[][] array3 = new int[array2[0][0]][array2[0][1]];
       for (int i = 1; i < array2.length; i++) {
           array3[array2[i][0]][array2[i][1]] = array2[i][2];
      }
       for (int[] ints : array3) {
           for (int anInt : ints) {
               System.out.print(anInt + "\t");
          }
           System.out.println();
      }
  }
}