回旋矩阵
这是深圳某处的一个面试题,要求打印出如下格式:
int i=5;
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
int i=6
1 2 3 4 5 6
20 21 22 23 24 7
19 32 33 34 25 8
18 31 36 35 26 9
17 30 29 28 27 10
16 15 14 13 12 11
解决方案1:
public class SnakePrint { private int orient = 0, length = 0, x = 0, y = 0; // orients为顺时针90°旋转方向,前进步长为1 private int[][] orients = { { 0, 1 }, { 1, 0 }, { 0, -1 }, { -1, 0 } }; private int[][] arrays; public SnakePrint(int length) { this.length = length; arrays = new int[length][length]; } // 根据当前方向返回下一个前进方向 private int[] nextOrient(int[] curOrient) { int nextX = x + curOrient[0], nextY = y + curOrient[1]; // 前进方向需要顺时针旋转90°了 if (nextX < 0 || nextX >= length || nextY < 0 || nextY >= length || arrays[nextX][nextY] != 0) { orient = ++orient % 4; return orients[orient]; } return curOrient; // 不需要掉头,返回原前进方向 } public void print() { int[] curOrient = orients[orient]; // 初始前进方向 for (int i = 1; i <= length * length; i++) { // 依次填充数组 arrays[x][y] = i; curOrient = nextOrient(curOrient); x += curOrient[0]; y += curOrient[1]; } for (int i = 0; i < length; i++) { for (int j = 0; j < length; j++) { System.out.printf("%4d", arrays[i][j]); // 按固定4个字符宽度的格式输出 } System.out.println(); } } public static void main(String[] args) { SnakePrint snakePrint = new SnakePrint(6); snakePrint.print(); } }
解决方案2:
public class SnakePrint { private int orient = 0, length = 0, x = 0, y = 0; // orients为顺时针90°旋转方向,前进步长为1 private int[][] orients = { { 0, 1 }, { 1, 0 }, { 0, -1 }, { -1, 0 } }; private int[][] arrays; public SnakePrint(int length) { this.length = length; arrays = new int[length][length]; } // 根据当前方向返回下一个前进方向 private int[] nextOrient(int[] curOrient) { int nextX = x + curOrient[0], nextY = y + curOrient[1]; // 前进方向需要顺时针旋转90°了 if (nextX < 0 || nextX >= length || nextY < 0 || nextY >= length || arrays[nextX][nextY] != 0) { orient = ++orient % 4; return orients[orient]; } return curOrient; // 不需要掉头,返回原前进方向 } public void print() { int[] curOrient = orients[orient]; // 初始前进方向 for (int i = 1; i <= length * length; i++) { // 依次填充数组 arrays[x][y] = i; curOrient = nextOrient(curOrient); x += curOrient[0]; y += curOrient[1]; } for (int i = 0; i < length; i++) { for (int j = 0; j < length; j++) { System.out.printf("%4d", arrays[i][j]); // 按固定4个字符宽度的格式输出 } System.out.println(); } } public static void main(String[] args) { SnakePrint snakePrint = new SnakePrint(6); snakePrint.print(); } }
以上代码来自:http://www.javaeye.com/topic/545378