# include <bits/stdc++.h>

using namespace std;
unsigned long long n;
int main(){
	cin>>n;
	while(n){
		cout<<n%10<<" ";
		n/=10;
	}
	return 0;
}

这题很简单，while循环保证AC:

#include <iostream>
using namespace std;
int main(){
	int n,shuwei;
	cin >> n;
	while(n){
		shuwei = n % 10;
		n /= 10;
		cout << shuwei << " ";
	}
	return 0;
}

#include<bits/stdc++.h> using namespace std; int main(){ int m; cin>>m; while(m!=0){ cout<<m%10<<" "; m=m/10; } return 0; }

#include<bits/stdc++.h> using namespace std ; int main ( ) { int m ; cin >> m ; while ( m != 0 ) { cout << m % 10 << " " ; m = m / 10 ; } return 0 ; }