1.二维数组转换为稀疏数组

2.稀疏数组转换二维数组

public class 二维数组与稀疏数组 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int [][] arr = {
                {0,0,0,0,0,0,0,0,0,0,0},
                {0,0,0,0,8,0,0,0,0,0,0},
                {0,0,0,0,0,0,0,0,0,0,0},
                {0,0,0,0,0,0,25,0,0,0,0},
                {0,0,0,0,0,0,0,0,0,0,0},
                {0,0,0,0,0,0,0,0,0,0,20},
                {0,0,0,0,0,0,0,0,0,0,0},
                {0,0,0,0,0,0,0,0,0,0,0},
                {0,0,0,5,0,0,0,0,0,0,0},
                {0,0,0,0,0,0,0,1,0,0,0},
                {0,0,0,0,0,0,0,0,0,0,0}
                };
        System.out.println("得到数组的长度为:"+getNum(arr, arr.length, arr[0].length));
        
        int [][] arrChange = new int[getNum(arr, arr.length, arr[0].length)+1][3];
        
        changeER(arr,11,11,arrChange,getNum(arr, arr.length, arr[0].length));
        
        for(int i = 0;i <= getNum(arr, arr.length, arr[0].length);i ++) {
            for(int j = 0;j < 3;j ++) {
                
                System.out.print(arrChange[i][j]+"    ");
                
            }
            
            System.out.println();
            
        }   
        int returnArr[][] = changeXS(arrChange);//定义新的二维数组用于存放转换之后的二维数组
        
        for(int i = 0;i < returnArr.length;i ++) {
            for(int j = 0;j < returnArr[0].length;j ++) {
                
                System.out.print(returnArr[i][j]+"    ");
                
            }
            
            System.out.println();
            
        }
        
    }
    private static int getNum(int [][] arr,int row,int col) {
        //得到共有多少有效数据
        int dataNum = 0;
        for(int i = 0;i < row; i ++) {
            for(int j = 0;j < col;j ++) {
                if(arr[i][j] != 0) {
                    dataNum ++ ;
                }
            }
        }
        return dataNum;
    }
    private static void changeER(int [][] arr,int row,int col,int [][]arrChange,int num) {//将二维数组转换为稀疏数组
        int n = 1;
        arrChange[0][0] = row;
        arrChange[0][1] = col;
        arrChange[0][2] = num;
        for(int i = 0;i < row; i ++) {
            for(int j = 0;j < col;j ++) {
                if(arr[i][j] != 0) {
                    arrChange[n][2] = arr[i][j];
                    arrChange[n][0] = i;
                    arrChange[n++][1] = j;
                }
            }
        }
    }
    private static int [][] changeXS(int [][]arrChange) {
        int [][] arr = new int [arrChange[0][0]][arrChange[0][1]];
        for(int i = 1;i < arrChange.length; i++) {
            arr[arrChange[i][0]][arrChange[i][1]] = arrChange[i][2];
        }
        return arr;
        
    }
}