代码如下

#include<bits/stdc++.h>
using namespace std;
int judge(int);
int main(){
    int x,y,num=0,amd[2000000]={0},judgement[2000000]={0};
    cin>>x>>y;
    for(int i=x;i<=y;i++){
    	amd[i]=i;
    	int p;
    	p=judge(amd[i]);
    	if(p==1){
    		judgement[i]=1;
    		num++;
		}else{
			judgement[i]=0;
		}
	}
	cout<<num<<"\n";
	for(int i=x;i<=y;i++){
		if(judgement[i]==1){
			cout<<amd[i]<<" ";
		}
      }
    	return 0;  
}
int judge(int year){
	if(year%400==0){
		return 1;
	}else if(year%4==0&&year%100!=0){
		return 1;
	}
	return 0;
}

大概是吧，仅供参考，拒绝无脑