Submission #1013774

#	Time	Username	Problem	Language	Result	Execution time	Memory
1013774		ReLice	Building 4 (JOI20_building4)	C++17	0 / 100	64 ms	73812 KiB

building4

#include <bits/stdc++.h>
#define ll long long
#define str string
#define ins insert
#define ld long double
#define pb push_back
#define pf push_front
#define pof pop_front()
#define pob pop_back()
#define lb lower_bound
#define ub upper_bound
#define endl "\n"
#define fr first
#define sc second
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define sz size()
#define vll vector<ll>
#define bc back()
#define arr array
#define pll vector<pair<ll,ll>>
using namespace std;/*
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define ordered_set tree<ll, null_type,less_equal<ll>, rb_tree_tag,tree_order_statistics_node_update>*/
template<class S,class T>
bool chmin(S &a,const T &b) {
	return a>b?(a=b)==b:false;
}
template<class S,class T>
bool chmax(S &a,const T &b) {
	return a<b?(a=b)==b:false;
}
//void fre(string s){freopen((s+".in").c_str(),"r",stdin);freopen((s+".out").c_str(),"w",stdout);}
void start(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
}
const ll inf=1e18;
const ll mod=998244353;
const ll N=3e3+7;
const ld eps=1e-9;
ll dp[N][N][2];
void solve(){
    ll i,j;
    ll n;
    cin>>n;
    ll a[n*2],b[n*2];
    for(i=0;i<n*2;i++)cin>>a[i];
    for(i=0;i<n*2;i++)cin>>b[i];
    dp[1][0][0]=1;
    dp[0][1][1]=1;
    for(ll len=1;len<2*n;len++){
        for(i=0;i<=len;i++){
            j=len-i;
            ll x=i+j-1;
            if(i>n || j>n) continue;
            if(i<n && a[x]<=a[x+1])dp[i+1][j][0]+=dp[i][j][0];
            if(j<n && a[x]<=b[x+1])dp[i][j+1][1]+=dp[i][j][0];
            if(i<n && b[x]<=a[x+1])dp[i+1][j][0]+=dp[i][j][1];
            if(j<n && b[x]<=b[x+1])dp[i][j+1][1]+=dp[i][j][1];
        }
    }
    if(!dp[n][n][0] && !dp[n][n][1]) { cout<<-1<<endl;return; }
    ll A=n,B=n,c,x=n*2-1;
    if(dp[n][n][0])c=0;
    else c=1;
    str ans;
    while(x){
        if(c==0){
            ans+='A';
            A--;
            if(!A || a[x]<a[x-1] || !dp[A][B][0]) c=1;
            x--;
        }else{
            ans+='B';
            B--;
            if(!B || b[x]<b[x-1] || !dp[A][B][1]) c=0;
            x--;
        }
    }
    if(A) ans+='A';
    else ans+='B';
    reverse(all(ans));
    cout<<ans<<endl;
}
signed main(){
    start();
    ll t=1;
    //cin>>t;
    while(t--) solve();
    return 0;
}
/*



*/

• Subtask 1: 0 / 11
• Subtask 2: 0 / 89