P5721的一种单循环思路
#include<iostream>
using namespace std;
int main() {
int n, ans,s;
cin >> n;
s = n;
ans = (1 + n) * n / 2;
for (int i = 1; i <= ans; i++)
{
printf("%02d", i);
if (i == s) {
s += --n;
printf("\n");
}
}
return 0;
}