矩阵

题一：顺时针转圈打印矩阵

    public void solve(int[][] matrix) {
        int line = matrix.length;
        int row = matrix[0].length;

        //其实把for改成while看起来更干净些，下面的print里也是
        //PS：row 英语原意是行 column是列
        int startLine = 0, startRow = 0, endLine = line-1, endRow = row-1;
        for (; startLine <= endLine && startRow <= endRow; startLine++,startRow++,endLine--,endRow--) {
            print(matrix, startLine, startRow, endLine, endRow);
        }
    }

    /**
     *
     * @param matrix 矩阵
     * @param startLine 左上角开始节点的行
     * @param startRow 左上角开始节点的列
     * @param endLine 右下角结束节点的行
     * @param endRow 右下角结束节点的列
     */
    private void print(int[][] matrix, int startLine, int startRow, int endLine, int endRow) {
        int i;
        if (startLine == endLine) {
            for (i = startRow; i <= endRow; i++) {
                System.out.print(matrix[startLine][i] + " ");
            }
            return;
        }
        if (startRow == endRow) {
            for (i = startLine; i <= endLine; i++) {
                System.out.print(matrix[i][startRow] + " ");
            }
            return;
        }
        for (i = startRow; i <= endRow; i++) {
            System.out.print(matrix[startLine][i] + " ");
        }

        for (i = startLine + 1; i <= endLine; i++) {
            System.out.print(matrix[i][endRow] + " ");
        }

        for(i = endRow-1; i >= startRow; i--) {
            System.out.print(matrix[endLine][i] + " ");
        }

        for (i = endLine-1; i > startLine; i--) {
            System.out.print(matrix[i][startRow] + " ");
        }
    }

    public static void main(String[] args) {
        Page331 instance = new Page331();

        int[][] matrix = {{1,2,3,4}, {10,11,12,5}, {9,8,7,6}};
        instance.solve(matrix);

        System.out.println();
        int[][] matrix2 = {{1,2,3},{8,9,4},{7,6,5}};
        instance.solve(matrix2);

        System.out.println();
        int[][] matrix3 = {{1,2,3,4,5},{18,19,20,21,6},{17,28,29,22,7},{16,27,30,23,8},{15,26,25,24,9},{14,13,12,11,10}};
        instance.solve(matrix3);

        System.out.println();
        int[][] matrix4 = {{1},{2},{3},{4}};
        instance.solve(matrix4);

        System.out.println();
        int[][] matrix5 = {{1,2,3,4,5}};
        instance.solve(matrix5);
    }

题二：“之“字形打印矩阵
"之"字形打印矩阵
两个指针：(sr,sc)先从第一行往右移动，到头就往下；(er,ec)第一列往下，到头往右
print方法里boolean控制打印方向，为true代表从下往上打印
注意 列比行长 与 行比列长 拐弯后不同的打印方向

    public void solve(int[][] matrix) {
        int rowL = matrix.length;
        int columnL = matrix[0].length;
        int sr = 0, sc = 0, er = 0, ec = 0;

        while (sc < columnL && er < rowL) {
            print(matrix, 0, sc, er, 0, (sc & 1) == 0);
            sc++;
            er++;
        }

第一个指针沿着第一行到头
        if (sc == columnL && er < rowL) {  
            while (er < rowL) {
                print(matrix, ++sr, columnL-1, er, 0, (er & 1) == 0);
                er++;
            }
            此时er == rowL，也就是需要拐弯向右
            while (sr < rowL-1) {
                print(matrix, ++sr, columnL-1, rowL-1, ++ec, (sr & 1) == 0);
            }
        } 
第二个指针沿着第一列到头
        else if (er == rowL && sc < columnL) {
            while (sc < columnL) {
                print(matrix, 0, sc, rowL-1, ++ec, (sc & 1) == 0);
                sc++;
            }
            此时sc == columnL，需要拐弯向下
            while (ec < columnL-1) {
                print(matrix, ++sr, columnL-1, rowL-1, ++ec, (sr & 1) == 1);
            }
        } 
方阵情况
        else {
            while (sr < rowL-1) {
                print(matrix, ++sr, columnL-1, rowL-1, ++ec, (sr & 1) == 0);
            }
        }
    }

    orientation = true代表从下向上打印
    private void print(int[][] matrix, int sr, int sc, int er, int ec, boolean orientation) {
        if (orientation) {
            while (er >= sr) {
                System.out.print(matrix[er][ec] + " ");
                er--;
                ec++;
            }
        } else {
            while (sr <= er) {
                System.out.print(matrix[sr][sc] + " ");
                sr++;
                sc--;
            }
        }
    }

    public static void main(String[] args) {
        Page335 instance = new Page335();

        //列长
        int[][] matrix = {{1,2,3,4}, {10,11,12,5}, {9,8,7,6}};
        instance.solve(matrix);

        //行长
        System.out.println();
        int[][] matrix3 = {{1,2,3,4,5},{18,19,20,21,6},{17,28,29,22,7},{16,27,30,23,8},{15,26,25,24,9},{14,13,12,11,10}};
        instance.solve(matrix3);
        System.out.println();
        System.out.print("1 2 18 17 19 3 4 20 28 16 15 27 29 21 5 6 22 30 26 14 13 25 23 7 8 24 12 11 9 10" + "正确顺序");

        //方阵
        System.out.println();
        int[][] matrix2 = {{1,2,3},{8,9,4},{7,6,5}};
        instance.solve(matrix2);

        //单列
        System.out.println();
        int[][] matrix4 = {{1},{2},{3},{4}};
        instance.solve(matrix4);

        //单行
        System.out.println();
        int[][] matrix5 = {{1,2,3,4,5}};
        instance.solve(matrix5);

        System.out.println();
        int[][] matrix6 = {{1,2,3,4,5},{6,7,8,9,10}};
        instance.solve(matrix6);

        System.out.println();
        int[][] matrix7 = {{1,2},{3,4},{5,6},{7,8}};
        instance.solve(matrix7);
    }