java实现“之“字型矩阵

      n * n

      1  3  4   10
      2  5  9   11
      6  8  12  15
      7  13 14  16

思路： 分为左上角、右下角、中间三部分，其中左上角和右下角和为N*N + 1,中间一部分为最长对角线，为(N*N-N)/2 = 6、6+1、 6+2、6+3、6+4。然后只需要把左上角填充完毕就行，一共有四个方向，下、右上、右、左下。OK思路有了接下来是编码

public class SnakeMatrix {

    /**
     * 蛇形矩阵
     * n * n
     * 1  3  4   10
     * 2  5  9   11
     * 6  8  12  15
     * 7  13 14  16
     */
    public static void main(String[] args) {
        int N = 5;
        int[][] matrix= new int[N][N];
        int value = 1;
        if(N % 2 == 0){
            int temp = (N*N - N) / 2;
            //N是偶数, 对角线赋值
           for(int i=N-1; i>=0; i--)
               matrix[i][N-1-i] = ++temp;
        }else{
            //N是奇数，对角线赋值
            int temp = (N*N - N) / 2;
            for(int i=0; i<N; i++)
                matrix[i][N-1-i] = ++temp;
        }

        final int DOWN = 0;
        final int RIGHT = 1;
        final int UPRIGHT = 2;
        final int LEFTDOWN = 3;
        int dir  = DOWN;
        matrix[0][0] = 1;
        int row = 0;
        int col = 0;

        while(value < (N*N - N) / 2){
            switch (dir){
                case DOWN:
                    row++;
                    if(row <= N-2){
                        value++;
                        matrix[row][col] = value;
                        dir = UPRIGHT;
                        break;
                    }
                case RIGHT:
                    col++;
                    if(col <= N-2){
                        value++;
                        matrix[row][col] = value;
                        dir = LEFTDOWN;
                        break;
                    }
                case UPRIGHT:
                    row--;
                    col++;
                    if(row >=0 ){
                        value++;
                        matrix[row][col] = value;
                        dir = UPRIGHT;
                        break;
                    }else{
                        row++;
                        col--;
                        dir = RIGHT;
                        break;
                    }
                case LEFTDOWN:
                    row++;
                    col--;
                    if(col >= 0){
                        value++;
                        matrix[row][col] = value;
                        dir = LEFTDOWN;
                        break;
                    }else{
                        col++;
                        row--;
                        dir = DOWN;
                        break;
                    }
            }
        }

        //根据对称性赋值
        for(int i = 0; i < N; i++)
            for(int j = 0; j < N; j++)
                if(matrix[i][j] == 0)
                    matrix[i][j] = N*N+1 - matrix[N-1-i][N-1-j];

        for(int i = 0; i < N; i++){
            for(int j = 0; j < N; j++){
                System.out.print(matrix[i][j] + "  ");
            }
            System.out.println();
        }

    }

}

java实现螺旋形蛇形矩阵

1  2  3  4
12 13 14 5
11 16 15 6
10 9  8  7

思路： 和上面一样，方式为右、下、左、上

public class SnakeMatrix {

    /**
     * 蛇形矩阵
     * n * n
     * 1  2  3  4
     * 12 13 14 5
     * 11 16 15 6
     * 10 9  8  7
     */
    public static void main(String[] args) {
        int N = 4;
        int[][] matrix = new int[N][N];
        int value = 1;
        final int RIGHT = 0;
        final int DOWN = 1;
        final int LEFT = 2;
        final int UP = 3;
        int dir = RIGHT;
        int row = 0;
        int col = 0;
        matrix[row][col] = value;
        while (value < N*N){
            switch (dir){
                case RIGHT:
                    col++;
                    if(col <= N-1 && matrix[row][col] == 0){
                        value++;
                        matrix[row][col] = value;
                        dir = RIGHT;
                        break;
                    }else{
                        col--;
                        dir = DOWN;
                        break;
                    }
                case DOWN:
                    row++;
                    if(row <= N-1 && matrix[row][col] == 0){
                        value++;
                        matrix[row][col] = value;
                        dir = DOWN;
                        break;
                    }else{
                        row--;
                        dir = LEFT;
                        break;
                    }
                case LEFT:
                    col--;
                    if(col>=0 && matrix[row][col] == 0){
                        value++;
                        matrix[row][col] = value;
                        dir = LEFT;
                        break;
                    }else{
                        col++;
                        dir = UP;
                        break;
                    }
                case UP:
                    row--;
                    if(row >= 0 && matrix[row][col] == 0){
                        value++;
                        matrix[row][col] = value;
                        dir = UP;
                        break;
                    }else{
                        row++;
                        dir = RIGHT;
                        break;
                    }
            }
        }
        for(int i = 0; i < N; i++){
            for(int j = 0; j < N; j++){
                System.out.print(matrix[i][j] + "  ");
            }
            System.out.println();
        }
    }

}

参考：蛇形矩阵的java实现