打印螺旋矩阵

see: http://www.geeksforgeeks.org/archives/10768

Print a given matrix in spiral form

August 20, 2011

Given a 2D array, print it in spiral form. See the following examples.

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


Input:
        1   2   3   4  5   6
        7   8   9  10  11  12
        13  14  15 16  17  18
Output: 
1 2 3 4 5 6 12 18 17 16 15 14 13 7 8 9 10 11

Answer:

/* Paste your code here (You may delete these lines if not writing code) */
void spiralmatrix(int arr[], int m, int n)
{
    int rowstart=0, rowend=m-1, colstart=0, colend=n-1;
    int i,j;
    while(rowstart<=rowend&&colstart<=colend)
    {
        int i=rowstart, j=colstart;
        for(j=colstart;j<=colend;j++)
        {
            printf("%d",arr[i][j]);
        }
        for(i=rowstart+1,j--;i<=rowend;i++)
        {
            printf("%d",arr[i][j]);
        }
        for(j=colend-1,i--;j>=colstart;j--)
        {
            printf("%d",arr[i][j]);
        }
        for(i=rowend-1,j++;i>=rowstart+1;i--)
        {
            printf("%d",arr[i][j]);
        }
        rowstart++, rowend--, colstart++,colend--;
    }
}