螺旋矩阵是指一个呈螺旋状的矩阵,它的数字由第一行开始到右边不断变大,向下变大,向左变大,向上变大,如此循环。(如图1)
1 2 3 4 5
16 17 18 19 6
15 24 25 20 7
14 23 22 21 8
13 12 11 10 9
/ * 输出螺旋矩阵 * * @author zhanliqing * */ public class SpiralMatrix { public static void main(String[] args) { int matrix[][] = new int[5][5]; // build(matrix, matrix.length); build(matrix, matrix.length, 0, matrix.length, 1); for (int i = 0; i < matrix.length; i++) { for (int j = 0; j < matrix[i].length; j++) { System.out.format("%5d", matrix[i][j]); } System.out.println(); } } / * 递归调用 * * @param matrix * @param num * 当前第几阶方阵 * @param from * 从哪个数值开始 * @param start * * @param len * 长度是多少 */ public static void build(int matrix[][], int num, int from, int len, int start) { if (num == 1) { matrix[from][from] = start; return; } else if (num == 2) { matrix[from][from] = start++; matrix[from][from + 1] = start++; matrix[from + 1][from + 1] = start++; matrix[from + 1][from] = start++; return; } else { for (int i = 0; i < len; i++) { matrix[from][i + from] = start++; } for (int i = 1; i < len; i++) { matrix[from + i][from + len - 1] = start++; } for (int i = len - 2; i >= 0; i--) { matrix[from + len - 1][from + i] = start++; } for (int i = len - 2; i > 0; i--) { matrix[from + i][from] = start++; } build(matrix, num - 2, from + 1, len - 2, start); } } / * 循环调用 * * @param matrix * @param num */ public static void build(int matrix[][], int num) { int count = 2; matrix[0][0] = 1; int i = 0, j = 0; while (count <= num * num) { while ((j + 1 < num) && matrix[i][j + 1] == 0) matrix[i][++j] = count++; while ((i + 1 < num) && matrix[i + 1][j] == 0) matrix[++i][j] = count++; while ((j - 1 >= 0) && matrix[i][j - 1] == 0) matrix[i][--j] = count++; while ((i - 1 >= 0) && matrix[i - 1][j] == 0) matrix[--i][j] = count++; } } }
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