AC代码，放心使用

#include <iostream>
using namespace std;
int main()
{
    int a, b, c, d;
    int n, m;
    cin >> n >> m;
    for (c = 0; c <= n; c += 3)
    {
        d = c / 3;
        for (b = 0; b <= n; b += 1)
        {
            for (a = 0; a <= n; a += 1)
            {
                if ((a + b + c == m) && (5 * a + 3 * b + d == n))
                {
                   cout << a << " " << b << " " << c << endl;   
                }
            }
        }
    }
    return 0;
}

#include <bits/stdc++.h>
using namespace std;
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n, m;
    cin >> n >> m;
    for (int i = 0; i <= m; i++)
    {
        for (int j = 0; j <= m; j++)
        {
            int k = m - i - j;
            if (i * 5 + j * 3 + k / 3 * 1 == n && k % 3 == 0)
                cout << i << " " << j << " " << k << endl;
        }
    }
    return 0;
}//以AC

#include <iostream>
using namespace std;
int main()
{
	int n, m;
	cin >> n >> m;
	for (int i = 0; i <= n / 5 + 1; i++)
	{
		for (int j = 0; j <= n / 3 + 1; j++)
		{
			if (14 * i + 8 * j == 3 * n - m)
			{
				cout << i << " " << j << " " << m - i - j << endl;
			}
		}
	}
	return 0;
}

#include <bits/stdc++.h>
using namespace std;
int n,m;
int main(){
	cin>>n>>m;
	for (int i=0;i<=ceil(n/5);i++){
		for (int j=0;j<=ceil(n/3);j++){
			int k=n-i*5-j*3;
			if (k*3+i+j==m)cout<<i<<" "<<j<<" "<<k*3<<endl;
		}
	}
	return 0;
}

#include<bits/stdc++.h>
using namespace std;
int n,m;
int main()
{
    cin>>n>>m;
    for(int i=0;i<=n/5;i++)
    {
        for(int j=0;j<=n/3;j++)
        {
            for(int k=0;k<=n*3;k++)
            {
                if(i*5+j*3+k/3==n&&i+j+k==m&&k%3==0)
                {
                    cout<<i<<" "<<j<<" "<<k<<endl;
                }
            }
        }
    }
    return 0;
}

#include <bits/stdc++.h>
using namespace std;
int n,m;
int main()
{
    cin>>n>>m;
    for(int i=0;i<=n;i++)
    {
        for(int j=0;j<=n;j++)
        {
            int k=(n-5*i-3*j)*3;
            if(i+j+k==m)
                cout<<i<<" "<<j<<" "<<k<<endl;
        }
    }
    return 0;
}

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int a, b, c;
    int n, m;
    cin >> n >> m;
    for (a = 0; a <= n/5; a += 1)
    {
        for (b = 0; b <= n/3; b += 1)
        {
            c = (n - 5*a - 3*b)*3;
			        
                if (a + b + c == m && c % 3 == 0)
                {
                   cout << a << " " << b << " " << c << endl;   
                }
            
        }
    }
    return 0;
}
不超时