二维数组(矩阵)对角线输出 - 代码物语-Let code talk - ITeye技术网站
- 二维数组(矩阵)对角线输出
- /**
- 二维数组 对角线输出 两个方向
- 例如对于数组:
- { 1, 2, 3, 4 },
- { 5, 6, 7, 8 },
- { 9, 10, 11, 12 },
- { 13, 14, 15, 16 },
- slash方向输出:
- 1
- 5 2
- 9 6 3
- 13 10 7 4
- 14 11 8
- 15 12
- 16
- backslash输出:
- 4
- 3 8
- 2 7 12
- 1 6 11 16
- 5 10 15
- 9 14
- 13
- 数组的行数和列数可以不相等,但同一行的元素个数必须相等,称为"矩阵"更合适
- */
- public class PrintArray {
- public static void main(String[] args) {
- /*// row != col:
- int[][] arr = new int[][] {
- { 1, 2, 3, 4 },
- { 5, 6, 7, 8 },
- { 9, 10, 11, 12 },
- //{ 13, 14, 15, 16 },
- };
- */
- int[][] arr = new int[][] {
- { 1, 2, 3, 4 },
- { 5, 6, 7, 8 },
- { 9, 10, 11, 12 },
- { 13, 14, 15, 16 },
- };
- slash(arr);
- System.out.println("======");
- backslash(arr);
- }
- public static void slash(int[][] arr) {
- if (arr == null) {
- throw new IllegalArgumentException("arr cannot be null");
- }
- int col = arr[0].length;
- int row = arr.length;
- for( int k = 0 ; k < col * 2 -1 ; k++ ) { //k代表有多少行输出,由col决定
- int sum = k; //同一行的元素,行下标和列下标的和相等
- for( int j = 0 ; j < col ; j++ ) {
- int i = sum - j;
- if(isValidIndex(i, row) && isValidIndex(j, col)) {
- System.out.print( arr[i][j] + " " );
- }
- }
- System.out.println();
- }
- }
- public static void backslash(int[][] arr) {
- if (arr == null) {
- throw new IllegalArgumentException("arr cannot be null");
- }
- int row = arr.length;
- int col = arr[0].length;
- for (int k = 0; k < col * 2 - 1; k++) { //k代表有多少行输出,由col决定
- int diff = col - k - 1; //同一行的元素,行下标和列下标的差相等
- for (int j = 0; j < col; j++) {
- int i = j - diff;
- if (isValidIndex(i, row) && isValidIndex(j, col)) {
- System.out.print(arr[i][j] + " ");
- }
- }
- System.out.println();
- }
- }
- private static boolean isValidIndex(int i, int n) {
- return i >= 0 && i < n;
- }
- }