普通

#include <iostream>
using namespace std;
int main()
{
    int n, m, x = 0;
    cin >> n >> m;
    for (int i = 1; i <= n; i ++)
    {
        for (int j = 1; j <= m; j ++)
        {
            x ++;
            if (x % m == 0) cout << "PUM" <<endl;
            else cout << x << ' ';
        }
    }
    return 0;
}

第二种写法

#include <iostream>
using namespace std;
int main()
{
    int n, m;
    cin >> n >> m;
    for (int i = 0, k = 1; i < n; i ++)
    {
        for (int j = 0; j < m -1; j ++)
        {
            cout << k << ' ';
            k ++;
        }
        cout << "PUM" <<endl;
        k ++;//k还要++
    }
    return 0;
}