算法（一）稀疏数组

经典案例：五子棋的分布、提取、再分布

public static void main(String[] args) {

        System.out.println("=============二维数据===========");
        int [][] arr = new int [11][11];

        arr[1][2] = 1;
        arr[2][3] = 2;

        int sum = 0;
        for (int[] ints : arr) {
            for (int anInt : ints) {
                System.out.printf("%d\t", anInt);
                if(anInt != 0){
                    sum ++;
                }
            }
            System.out.println();
        }
        // 创建稀疏数据
        int [][] sparseArr = new int [sum + 1][3];
        // 每行共有3列，第一行分别存放 行数、列数、非0的值的个数，后面每行分别存放 第几行、第几列、对应的值
        sparseArr[0][0] = 11;
        sparseArr[0][1] = 11;
        sparseArr[0][2] = sum;
        int count = 0;
        for (int i = 0; i < 11; i++) {
            for (int j = 0; j < 11; j++) {
                int num = arr[i][j];
                if(num != 0){
                    count ++;
                    sparseArr[count][0] = i;
                    sparseArr[count][1] = j;
                    sparseArr[count][2] = num;
                }
            }
        }
        System.out.println("=============稀疏数据===========");
        for (int[] ints : sparseArr) {
            for (int anInt : ints) {
                System.out.printf("%d\t", anInt);
                if(anInt != 0){
                    sum ++;
                }
            }
            System.out.println();
        }

        System.out.println("=============稀疏数据还原成二维数据===========");
        int [][] arr2 = new int [sparseArr[0][0]][sparseArr[0][1]];
        for (int i = 1; i < sparseArr.length; i++) {
            arr2[sparseArr[i][0]][sparseArr[i][1]] = sparseArr[i][2];
        }
        for (int[] ints : arr2) {
            for (int anInt : ints) {
                System.out.printf("%d\t", anInt);
                if(anInt != 0){
                    sum ++;
                }
            }
            System.out.println();
        }

    }