#include <iostream>
using namespace std;
int main()
{
    int n;
    cin >> n;
    while (!(n % 2))
    {
        cout << 2 << " ";
        n /= 2;
    }
    for (int i = 3; i <= n; i += 2)
    {
        while (!(n % i))
        {
            cout << i << " ";
            n /= i;
        }
    }
    return 0;
}

#include <bits/stdc++.h>
using namespace std;
int n;
int main()
{
    cin>>n;
    for(int i=2;i*i<=n;i++)
        while(n%i==0){
            cout<<i<<" ";
            n/=i;
        }
    if(n!=1) cout<<n;
    return 0;
}

记得点赞！

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n,i=2;
    cin>>n;
    while(n!=1)
    {
        if(n%i==0)
        {
            cout<<i<<" ";
            n/=i;
            
        }
        else
        {
            i++;
        }
    }
    return 0;
}

#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n;
	cin >> n;
	int i = 2;
	while(n != 1){
		if(n%i == 0){
			cout << i << " ";
			n /= i;
		}
		else {
			i++;
		}
	}
	return 0;
}

真正的标准做法（）

#include<bits/stdc++.h>
using namespace std;
int n,p[100],x;
bool prime(int xx)
{
    for (int i=2;i*i<=xx;i++)
        if (xx%i==0)
            return 0;
    return 1;
}
int main()
{
    cin>>n;
    for (int i=2;i<=1000;i++)
        if (prime(i))
        {
            p[++x]=i;
        }
    while (n>1)
        for (int i=1;i<=x;i++)
            if (n%p[i]==0)
            {
                cout<<p[i]<<" ";
                n/=p[i];
                break;
            }
    return 0;
}