稀疏数组

以下代码把11*11的棋盘转化为稀疏数组，再把稀疏数组转化为普通的矩阵（即棋盘）。

package com.cxf.array; 
 
import java.util.Arrays; 
 
public class Demo2 { 
    public static void main(String[] args) { 
        int[][] chess1 = new int[11][11]; 
        int num_val = 0; 
        int count = 1; 
        chess1[2][3] = 1; 
        chess1[3][4] = 2; 
 
        System.out.println("Original chess board:"); 
        for (int i = 0; i < 11; i++) { 
            for (int j = 0; j < 11; j++) { 
                System.out.print(chess1[i][j]+"\t"); 
                if(chess1[i][j] != 0) { 
                    num_val++; 
                } 
            } 
            System.out.println(); 
        } 
 
        int[][] sparse = new int[num_val + 1][3];   //create a sparse matrix 
        sparse[0][0] = 11; 
        sparse[0][1] = 11; 
        sparse[0][2] =num_val; 
        for (int i = 0; i < 11; i++) { 
            for (int j = 0; j < 11; j++) { 
                if(chess1[i][j] != 0) { 
                    sparse[count][0] = i; 
                    sparse[count][1] = j; 
                    sparse[count][2] = chess1[i][j]; 
                    count++; 
                } 
            } 
        } 
        System.out.println("=========================================="); 
        System.out.println("sparce matrix:"); 
        for (int i = 0; i < num_val + 1; i++) { 
            System.out.println(Arrays.toString(sparse[i])); 
        } 
        System.out.println("=========================================="); 
 
        System.out.println("turn the sparce matrix to chess board:"); 
        int[][] chess2 = new int[sparse[0][0]][sparse[0][1]]; 
        for (int i = 1; i <= sparse[0][2]; i++) { 
            chess2[sparse[i][0]][sparse[i][1]] = sparse[i][2]; 
        } 
 
        //print chess2 
        for (int[] ints : chess2) { 
            for (int anInt : ints) { 
                System.out.print(anInt + "\t"); 
            } 
            System.out.println(); 
        } 
    } 
} 
 

输出结果：

Original chess board: 
0	0	0	0	0	0	0	0	0	0	0	 
0	0	0	0	0	0	0	0	0	0	0	 
0	0	0	1	0	0	0	0	0	0	0	 
0	0	0	0	2	0	0	0	0	0	0	 
0	0	0	0	0	0	0	0	0	0	0	 
0	0	0	0	0	0	0	0	0	0	0	 
0	0	0	0	0	0	0	0	0	0	0	 
0	0	0	0	0	0	0	0	0	0	0	 
0	0	0	0	0	0	0	0	0	0	0	 
0	0	0	0	0	0	0	0	0	0	0	 
0	0	0	0	0	0	0	0	0	0	0	 
========================================== 
sparce matrix: 
[11, 11, 2] 
[2, 3, 1] 
[3, 4, 2] 
========================================== 
turn the sparce matrix to chess board: 
0	0	0	0	0	0	0	0	0	0	0	 
0	0	0	0	0	0	0	0	0	0	0	 
0	0	0	1	0	0	0	0	0	0	0	 
0	0	0	0	2	0	0	0	0	0	0	 
0	0	0	0	0	0	0	0	0	0	0	 
0	0	0	0	0	0	0	0	0	0	0	 
0	0	0	0	0	0	0	0	0	0	0	 
0	0	0	0	0	0	0	0	0	0	0	 
0	0	0	0	0	0	0	0	0	0	0	 
0	0	0	0	0	0	0	0	0	0	0	 
0	0	0	0	0	0	0	0	0	0	0	 

稀疏数组只记录普通数组中特殊点的位置和值。