C++, other, spiral_print.cpp

/**
* @file
* @brief Print the elements of a matrix traversing it spirally
*/
#include <iostream>

/** Arrange sequence of numbers from '1' in a matrix form
* \param [out] a matrix to fill
* \param [in] r number of rows
* \param [in] c number of columns
*/
void genArray(int **a, int r, int c) {
int value = 1;
for (int i = 0; i < r; i++) {
for (int j = 0; j < c; j++) {
a[i][j] = value;
std::cout << a[i][j] << " ";
value++;
}
std::cout << std::endl;
}
}

/** Traverse the matrix spirally and print the sequence of elements
* \param [in] a matrix to read from
* \param [in] r number of rows
* \param [in] c number of columns
*/
void spiralPrint(int **a, int r, int c) {
int startRow = 0, endRow = r - 1;
int startCol = 0, endCol = c - 1;
int cnt = 0;

while (startRow <= endRow && startCol <= endCol) {
/// Print start row
for (int i = startCol; i <= endCol; i++, cnt++) {
std::cout << a[startRow][i] << " ";
}
startRow++;

/// Print the end col
for (int i = startRow; i <= endRow; i++, cnt++) {
std::cout << a[i][endCol] << " ";
}
endCol--;

/// Print the end row
if (cnt == r * c) {
break;
}

for (int i = endCol; i >= startCol; i--, cnt++) {
std::cout << a[endRow][i] << " ";
}
endRow--;

/// Print the start Col
if (cnt == r * c) {
break;
}
for (int i = endRow; i >= startRow; i--, cnt++) {
std::cout << a[i][startCol] << " ";
}
startCol++;
}
}

/** main function */
int main() {
int r, c;
std::cin >> r >> c;
int **a = new int *[r];
for (int i = 0; i < r; i++) a[i] = new int[c];

genArray(a, r, c);
spiralPrint(a, r, c);

for (int i = 0; i < r; i++) delete[] a[i];
delete[] a;
return 0;
}