XDU1131 思维+dp优化

#include <cstdio>
#include <algorithm>
#include <cstring>
#include <vector>
#include <iostream>
#include <cmath>
#include <queue>
#include <ctime>
using namespace std;
#define lson l,(l+r)/2,rt<<1
#define rson (l+r)/2+1,r,rt<<1|1
#define dbg(x) cout<<#x<<" = "<< (x)<< endl
#define pb push_back
#define fi first
#define se second
#define ll long long
#define sz(x) (int)(x).size()
#define pll pair<long long,long long>
#define pii pair<int,int>
#define pq priority_queue
vector<pll> v;
int dp[1010][1010];
ll a[1010];
int main(){
    int n;
    while(scanf("%d",&n)!=EOF){
        v.clear();
        for(int i=1;i<=n;i++){
            scanf("%lld",&a[i]);
            v.pb({a[i],i});
        }
        if(n==1){
            printf("1\n%lld\n",a[1]);
            continue;
        }
        sort(v.begin(),v.end());
        pll res;int cnt=0;
        for(int i=n-1;i>=1;i--){
            for(int j=i+1;j<=n;j++){
                auto it=lower_bound(v.begin(),v.end(),(pll){a[i]+a[j],j+1});
                if(it!=v.end() && it->fi==a[i]+a[j]){
                    dp[i][j]=dp[j][it->se]+1;
                }else{
                    dp[i][j]=2;
                }
                if(dp[i][j]>cnt || (dp[i][j]==cnt && (pll){a[i],a[j]}<res)){
                    res={a[i],a[j]};
                    cnt=dp[i][j];
                }
            }
        }
        printf("%d\n",cnt);
        printf("%lld %lld",res.fi,res.se);
        for(int i=2;i<cnt;i++){
            printf(" %lld",res.fi+res.se);
            res.fi+=res.se;
            swap(res.fi,res.se);
        }
        printf("\n");
    }
    return 0;
}