直接AC了好吧

我们要注意存放偶数时的下标问题！

#include<iostream>
using namespace std;
bool complete_even(int n){
    while(n>0){
        if(n%10%2!=0)return 0;
        n/=10;
    }return 1;
}
signed main(){
    int n,m,evens[4045],idx=-1;
    cin>>n>>m;
    for(int i=n;i<=m;i++)if(complete_even(i))evens[++idx]=i;
    for(int i=0;i<=idx;i++){
        if(i!=idx)cout<<evens[i]<<",";
        else cout<<evens[i];
    }
}