achen
#include<bits/stdc++.h> using namespace std; const int N=1e6+4; typedef long long ll; ll mod=998244353; ll ksm(ll x,ll pow){ ll ans=1,res=x; while(pow){ if(pow&1) ans=1ull*ans*res%mod; res=1ull*res*res%mod; pow>>=1; } return ans; } int nn[N],aa[N],bb[N]; ll ans4[N]; int main(){ int T;int mx=0; scanf("%d",&T); for(int i=1;i<=T;i++){ scanf("%d%d%d",&nn[i],&aa[i],&bb[i]); mx=max(mx,nn[i]); } ans4[1]=1,ans4[2]=1; ans4[3]=1,ans4[4]=2; for(int i=5;i<=mx;i+=2){ ans4[i]=(ans4[i-1]+ans4[i-3])%mod; ans4[i+1]=(ans4[i]+ans4[i-2])%mod; } for(int i=1;i<=T;i++){ int n=nn[i],a=aa[i],b=bb[i]; if(a==n-1&&b==n){ puts("1"); continue; } if(a==n&&b==n-1){ puts("1"); continue; } if(a==1&&b==2){ puts("1"); continue; } if(a==2&&b==1){ puts("1"); continue; } if((a+1)==b||(b+1)==a){ puts("0"); continue; } if(n==2){ puts("1"); continue; } if(a==1&&b==n){ printf("%lld\n",ans4[n]); continue; } if(a==n&&b==1){ printf("%lld\n",ans4[n]); continue; } if(a==1){ b--; printf("%lld\n",ans4[b]); continue; } if(b==1){ a--; printf("%lld\n",ans4[a]); continue; } int mnn=min(a,b),mxx=max(a,b); if(mxx==n){ if(mnn%2==1&&mxx%2==1){ int tpp=mnn+1; int tpp2=mxx-tpp+1; printf("%lld\n",ans4[tpp2]); continue; } if(mnn%2==1&&mxx%2==0){ int tpp=mnn+1; int tpp2=mxx-tpp+1; printf("%lld\n",ans4[tpp2]); continue; } int tpp=mnn+1; int tpp2=mxx-tpp+1; printf("%lld\n",ans4[tpp2]); continue; } int tp1=mnn+1,tp2=mxx-1; printf("%lld\n",ans4[tp2-tp1+1]); continue; } }细节题，这种题一定要多造几组数据判断
