20_稀疏数组

06_稀疏数组

1. 当一个数组中大部分元素为0或为同一值时，可以使用稀疏数组保存该数组。

//创建一个11*11的二维数组，0没有棋子，1黑棋，2白棋
int[][] array = new int[11][11];
array[1][2] = 1;
array[2][3] = 2;
System.out.println("原始数组array为：");
for (int[] ints : array) {
    for (int anInt : ints) {
        System.out.print(anInt + "\t");
    }
    System.out.println();
}

int sum = 0;
for (int i = 0; i < 11; i++) {
    for (int j = 0; j < 11; j++) {
        if(array[i][j] != 0){
            sum++;
        }
    }
}
System.out.println("有效值个数：" + sum);

//创建一个稀疏数组
int[][] array2 = new int[sum+1][3];
//11行11列，有效数为sum个
array2[0][0] = 11;
array2[0][1] = 11;
array2[0][2] = sum;
int a = 1;
for (int i = 0; i < 11; i++) {
    for (int j = 0; j < 11; j++) {
        if(array[i][j] != 0){
            array2[a][0] = i;
            array2[a][1] = j;
            array2[a][2] = array[i][j];
            a++;
        }
    }
}
System.out.println("稀疏矩阵array2为：");
for (int[] ints : array2) {
    for (int anInt : ints) {
        System.out.print(anInt + "\t");
    }
    System.out.println();
}

int[][] array3 = new int[array2[0][0]][array2[0][1]];
int b = 1;
for (int i = 0; i < array2[0][0]; i++) {
    for (int j = 0; j < array2[0][1]; j++) {
        if(i == array2[b][0] && j == array2[b][1]){
            array3[i][j] = array2[b][2];
            if(b < array2[0].length - 1){
                b++;
            }
        }else{
            array3[i][j] = 0;
        }
    }
}
System.out.println("解压后的数组array3为：");
for (int[] ints : array3) {
    for (int anInt : ints) {
        System.out.print(anInt + "\t");
    }
    System.out.println();
}

原始数组array为：
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	0	
0	0	0	0	0	0	0	0	0	0	0	
有效值个数：2
稀疏矩阵array2为：
11	11	2	
1	2	1	
2	3	2	
解压后的数组array3为：
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	0	
0	0	0	0	0	0	0	0	0	0	0

小提示

1. IDEA中可通过敲出array.for快速打出增强for循环。