Print Matrix Diagonally

Given a 2D matrix, print all elements of the given matrix in diagonal order. For example, consider the following 5 X 4 input matrix.

    1     2     3     4
    5     6     7     8
    9    10    11    12
   13    14    15    16
   17    18    19    20  (5x4)

Diagonal printing of the above matrix is

    1
    5     2
    9     6     3
   13    10     7     4
   17    14    11     8
   18    15    12
   19    16
   20

Following is C++ code for diagonal printing.

The diagonal printing of a given matrix ‘matrix[ROW][COL]‘ always has ‘ROW + COL – 1′ lines in output

#include <stdio.h> #include <stdlib.h>   #define ROW 5 #define COL 4   int min(int a, int b) { return (a < b)? a: b; }   int min(int a, int b, int c) { return min(min(a, b), c);}   int max(int a, int b) { return (a > b)? a: b; }   void diagonalOrder(int matrix[][COL]) {     for (int line=1; line<=(ROW + COL -1); line++)     {         /* Get column index of the first element in this line of output. The index is 0 for first ROW lines and line - ROW for remaining            lines  */         int start_col =  max(0, line-ROW);           /* Get count of elements in this line. The count of elements is            equal to minimum of line number, COL-start_col and ROW */          int count = min(line, (COL-start_col), ROW);         for (int j=0; j<count; j++)             printf("%5d ", matrix[min(ROW, line)-j-1][start_col+j]);           /* Ptint elements of next diagonal on next line */         printf("\n");     } }   void printMatrix(int matrix[ROW][COL]) {     for (int i=0; i< ROW; i++)     {         for (int j=0; j<COL; j++)             printf("%5d ", matrix[i][j]);         printf("\n");     } }   int main() {     int M[ROW][COL] = {{1, 2, 3, 4},                        {5, 6, 7, 8},                        {9, 10, 11, 12},                        {13, 14, 15, 16},                        {17, 18, 19, 20},                       };     printf ("Given matrix is \n");     printMatrix(M);       printf ("\nDiagonal printing of matrix is \n");     diagonalOrder(M);     return 0; }