#include <iostream>
using namespace std;
int main() {
const int M = 5, N = 3;
int matrix[M][N] = {
{1, 2, 3},
{4, 5, 6},
{7, 8, 9},
{10, 11, 12},
{13, 14, 15}
};
for (int i = 0; i < M; i++) {
if (i % 2 == 0) { // 从左到右
for (int j = 0; j < N; j++) {
cout << matrix[i][j] << " ";
}
} else { // 从右到左
for (int j = N - 1; j >= 0; j--) {
cout << matrix[i][j] << " ";
}
}
cout << endl;
}
return 0;
}