算法 回旋矩阵

http://www.iteye.com/topic/545378

一个画图程序 要求打印出

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

From caiwenhn2008

class snakePrint {
	static int length = 7;
	static int value = 1;
	static int[][] snake = new int[length][length];
	static Direction lastDirection = Direction.Right;

	static enum Direction {
		Right, Down, Left, Up;
	}

	public static void initialArray() {
		int row = 0, line = 0;
		for (int c = 0; c < length * length; c++) {
			snake[row][line] = value;
			lastDirection = findDirection(row, line);
			switch (lastDirection) {
				case Right:
					line++;
					break;
				case Down:
					row++;
					break;
				case Left:
					line--;
					break;
				case Up:
					row--;
					break;
				default:
					System.out.println("error");
			}
			value++;
		}
	}

	static Direction findDirection(int row, int line) {
		Direction direction = lastDirection;
		switch (direction) {
			case Right: {
				if ((line == length - 1) || (snake[row][line + 1] != 0))
					direction = direction.Down;
				break;
			}
			case Down: {
				if ((row == length - 1) || (snake[row + 1][line] != 0))
					direction = direction.Left;
				break;
			}
			case Left: {
				if ((line == 0) || (snake[row][line - 1] != 0))
					direction = direction.Up;
				break;
			}
			case Up: {
				if (snake[row - 1][line] != 0)
					direction = direction.Right;
				break;
			}
		}
		return direction;
	}

	public static void main(String[] args) {
		initialArray();

		// display.....
		for (int i = 0; i < length; i++) {
			for (int j = 0; j < length; j++) {
				System.out.print(snake[i][j] + "  ");
			}
			System.out.println();
		}
	}
}

From zhangcong170

public static void main(String args[]){
	  int N=5;
	  int a[][]=new int[N][N];
	  int i=0,j=0;
	  int count=1;
	  for(i=0;i<N;i++){
		  for(j=0;j<N;j++){
			  a[i][j]=0;
		  }
	  }
	  i=0;
	  j=0;
      for(int k=0;k<=N/2;k++){
    	  i=k;
    	  j=k;
		  for(i=k;i<N-k;i++){
			  a[j][i]=count;
			  count++;
		  }
		  i=N-k-1;
		  for(j=k+1;j<N-k;j++){
			  a[j][i]=count;
			  count++;
		  }
		  j=N-k-1;
		  for(i=N-k-2;i>=k;i--){
			  a[j][i]=count;
			  count++;
		  }
		  i=k;
		  for(j=N-k-2;j>=1+k;j--){
			  a[j][i]=count;
			  count++;
		  }
      }
		 
	  for(i=0;i<N;i++){
		  for(j=0;j<N;j++){
		     System.out.print(a[i][j]+" ");
		  }
		  System.out.println();
	  }
}

From yuonch   很好的解法

	public static void print(int count) {
		int is[][] = new int[count][count];
		int i = 0;
		int c = count * count;
		// 横向坐标累加器
		int j = 0;
		// 纵向坐标累加器
		int k = 0;
		// 横纵向控制，1为横向，-1为纵向
		int m = 1;
		// 坐标累加器，1为递增，-1为递减
		int n = 1;
		while (i < c) {
			is[j][k] = ++i;
			if (m > 0) {
				k += n;
				// 触边转向
				if (k < 0 || k >= count || is[j][k] != 0) {
					m *= -1;
					k -= n;
					j += n;
				}
			} else {
				j += n;
				// 触边转向
				if (j < 0 || j >= count || is[j][k] != 0) {
					m *= -1;
					j -= n;
					n *= -1;
					k += n;
				}
			}
		}

		for (int p = 0; p < count; ++p) {
			for (int q = 0; q < count; ++q)
				System.out.print(is[p][q] + "\t");
			System.out.println();
		}
	}

From homoclinic   有意思

public class mathsnake {
	static int L=8;
	static int start=1;
	static int snake[][]=new int[L][L];
	static int x=0,y=0;
	public static void main (String[] arg){
		double a=Math.PI;
		int m=0;
		for(int i=1;i<=L*L;i++){
			snake[x][y]=i;
			x=x+(int)Math.sin(m*a/2);
			y=y+(int)Math.cos(m*a/2);
			if(x==y||x+y==L-1){
				m=m+1;
				if(m>3){m=m-4;x++;y++;}
			}
		}
		 for (int i = 0; i < L; i++) {   
	            for (int j = 0; j < L; j++) {   
	                System.out.print(snake[i][j] + "  ");   
	            }   
	            System.out.println();   
	        }	
	}

}