【面试题二十】顺时针打印矩阵

顺时针打印矩阵

输入一个矩阵，按照从外到里的顺序打印出每一个数字，

如果只有一行，那么就不用第二步了，

第二步的前提条件是终止行号大于起始行号。

第三步的前提条件是圈内至少要有两行两列，也就是说除了终止行号要大于起始行号外，还要求终止利好大于起始列号；

同理第四步的前提条件是要有三行两列，因此要求终止行号比起始行号至少大2，同时终止列号大于起始列号；

PrintMatrix.cpp:

#include <iostream>
#include <cstdio>

using namespace std;

void PrintMatrixInCircle(int ** numbers, int columns, int rows, int start);
void PrintNumber(int number);

void PrintMatrixClockwisely(int** numbers, int columns, int rows)
{
	if(numbers == NULL || columns <= 0 || rows <= 0)
	{
		return ;
	}

	int start = 0;
	while(columns > start * 2 && rows > start * 2)
	{
		PrintMatrixInCircle(numbers, columns, rows, start);
		++start;
	}
}

void PrintMatrixInCircle(int **numbers, int columns, int rows, int start)
{
	int endX = columns - 1 - start;
	int endY = rows - 1 - start;

	/*从左到右打印一行*/
	for(int i = start; i <= endX; ++i)
	{
		int number = numbers[start][i];
		PrintNumber(number);
	}
	/*从上到下打印一列*/
	if(start < endY)
	{
		for(int i = start + 1; i <= endY; ++i)
		{
			int number = numbers[i][endX];
			PrintNumber(number);
		}
	}
	/*从右到左打印一行*/
	if(start < endX && start < endY)
	{
		for(int i = endX - 1; i >= start; --i)
		{
			int number = numbers[endY][i];
			PrintNumber(number);
		}
	}
	/*从下到上打印一行*/
	if(start < endX && start < endY - 1)
	{
		for(int i = endY - 1; i >= start + 1; --i)
		{
			int number = numbers[i][start];
			PrintNumber(number);
		}
	}
}

void PrintNumber(int number)
{
	cout<<number<<"\t";
}

// ====================测试代码====================
void Test(int columns, int rows)
{
    printf("Test Begin: %d columns, %d rows.\n", columns, rows);

    if(columns < 1 || rows < 1)
        return;

    int** numbers = new int*[rows];
    for(int i = 0; i < rows; ++i)
    {
        numbers[i] = new int[columns];
        for(int j = 0; j < columns; ++j)
        {
            numbers[i][j] = i * columns + j + 1;
        }
    }

    PrintMatrixClockwisely(numbers, columns, rows);
    printf("\n");

    for(int i = 0; i < rows; ++i)
        delete[] (int*)numbers[i];

    delete[] numbers;
}

int main()
{
    /*
    1    
    */
    Test(1, 1);

    /*
    1    2
    3    4
    */
    Test(2, 2);

    /*
    1    2    3    4
    5    6    7    8
    9    10   11   12
    13   14   15   16
    */
    Test(4, 4);

    /*
    1    2    3    4    5
    6    7    8    9    10
    11   12   13   14   15
    16   17   18   19   20
    21   22   23   24   25
    */
    Test(5, 5);

    /*
    1
    2
    3
    4
    5
    */
    Test(1, 5);

    /*
    1    2
    3    4
    5    6
    7    8
    9    10
    */
    Test(2, 5);

    /*
    1    2    3
    4    5    6
    7    8    9
    10   11   12
    13   14   15
    */
    Test(3, 5);

    /*
    1    2    3    4
    5    6    7    8
    9    10   11   12
    13   14   15   16
    17   18   19   20
    */
    Test(4, 5);

    /*
    1    2    3    4    5
    */
    Test(5, 1);

    /*
    1    2    3    4    5
    6    7    8    9    10
    */
    Test(5, 2);

    /*
    1    2    3    4    5
    6    7    8    9    10
    11   12   13   14    15
    */
    Test(5, 3);

    /*
    1    2    3    4    5
    6    7    8    9    10
    11   12   13   14   15
    16   17   18   19   20
    */
    Test(5, 4);

    return 0;
}

Makefile:

.PHONY:clean
CPP=g++
CFLAGS=-Wall -g
BIN=test
OBJS=PrintMatrix.o
LIBS=
$(BIN):$(OBJS)
	$(CPP) $(CFLAGS) $^ -o $@ $(LIBS)
%.o:%.cpp
	$(CPP) $(CFLAGS) -c $< -o $@
clean:
	rm -f *.o $(BIN)

运行结果：

Test Begin: 1 columns, 1 rows.
1
Test Begin: 2 columns, 2 rows.
1       2       4       3
Test Begin: 4 columns, 4 rows.
1       2       3       4       8       12      16      15      14      13      9       5       6       7       11      10
Test Begin: 5 columns, 5 rows.
1       2       3       4       5       10      15      20      25      24      23      22      21      16      11      6       7       8       9   14       19      18      17      12      13
Test Begin: 1 columns, 5 rows.
1       2       3       4       5
Test Begin: 2 columns, 5 rows.
1       2       4       6       8       10      9       7       5       3
Test Begin: 3 columns, 5 rows.
1       2       3       6       9       12      15      14      13      10      7       4       5       8       11
Test Begin: 4 columns, 5 rows.
1       2       3       4       8       12      16      20      19      18      17      13      9       5       6       7       11      15      14  10
Test Begin: 5 columns, 1 rows.
1       2       3       4       5
Test Begin: 5 columns, 2 rows.
1       2       3       4       5       10      9       8       7       6
Test Begin: 5 columns, 3 rows.
1       2       3       4       5       10      15      14      13      12      11      6       7       8       9
Test Begin: 5 columns, 4 rows.
1       2       3       4       5       10      15      20      19      18      17      16      11      6       7       8       9       14      13  12