Submission #707359

#	Time	Username	Problem	Language	Result	Execution time	Memory
707359		urosk	Building 4 (JOI20_building4)	C++14	100 / 100	276 ms	67788 KiB

building4

#define here cerr<<"===========================================\n"
#define dbg(x) cerr<<#x<<": "<<x<<endl;
#include "bits/stdc++.h"
//#include <ext/pb_ds/tree_policy.hpp>
//#include <ext/pb_ds/assoc_container.hpp>
#define ld double
#define ll long long
#define llinf 100000000000000000LL // 10^17
#define pb push_back
#define popb pop_back
#define fi first
#define sc second
#define endl '\n'
#define pll pair<ll,ll>
#define pld pair<ld,ld>
#define all(a) a.begin(),a.end()
#define ceri(a,l,r) {cerr<<#a<<": ";for(ll i_ = l;i_<=r;i_++) cerr<<a[i_]<< " ";cerr<<endl;}
#define cer(a) {cerr<<#a<<": ";for(ll x_ : a) cerr<<x_<< " ";cerr<<endl;}

#define daj_mi_malo_vremena ios_base::sync_with_stdio(false);cerr.tie(0);cout.tie(0);cin.tie(0);

using namespace std;
//using namespace __gnu_pbds;
/*
ll add(ll x,ll y){
    x+=y;
    if(x<0){
        x%=mod;
        x+=mod;
    }else{
        if(x>=mod) x%=mod;
    }
    return x;
}
ll mul(ll a,ll b){
	ll ans = (a*b)%mod;
	if(ans<0) ans+=mod;
	return ans;
}
typedef tree<int,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update> ordered_set;
typedef tree<int,null_type,less_equal<ll>,rb_tree_tag,tree_order_statistics_node_update> ordered_multiset;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll rnd(ll l,ll r){
    return uniform_int_distribution<ll>(l,r)(rng);
}
*/
#define maxn 1000005
ll n;
ll a[maxn],b[maxn];
pll dpa[maxn],dpb[maxn];
void tc(){
    cin >> n;
    n*=2;
    for(ll i = 1;i<=n;i++) cin >> a[i];
    for(ll i = 1;i<=n;i++) cin >> b[i];
    dpa[n] = {1,1};
    dpb[n] = {0,0};
    for(ll i = n-1;i>=1;i--){
        dpa[i] = dpb[i] = {n,-n};
        if(a[i]<=a[i+1]){
            dpa[i].fi = min(dpa[i].fi,dpa[i+1].fi+1);
            dpa[i].sc = max(dpa[i].sc,dpa[i+1].sc+1);
        }
        if(a[i]<=b[i+1]){
            dpa[i].fi = min(dpa[i].fi,dpb[i+1].fi+1);
            dpa[i].sc = max(dpa[i].sc,dpb[i+1].sc+1);
        }
        if(b[i]<=a[i+1]){
            dpb[i].fi = min(dpb[i].fi,dpa[i+1].fi);
            dpb[i].sc = max(dpb[i].sc,dpa[i+1].sc);
        }
        if(b[i]<=b[i+1]){
            dpb[i].fi = min(dpb[i].fi,dpb[i+1].fi);
            dpb[i].sc = max(dpb[i].sc,dpb[i+1].sc);
        }
    }
    bool oka = 1,okb = 1;
    if(dpa[1].fi>n/2||dpa[1].sc<n/2) oka = 0;
    if(dpb[1].fi>n/2||dpb[1].sc<n/2) okb = 0;
    if(!oka&&!okb){cout<<-1<<endl;return;}
    ll x = 0,cnt = n/2;
    for(ll i = 1;i<=n;i++){
        if(x<=a[i]&&dpa[i].fi<=cnt&&dpa[i].sc>=cnt){
            cout<<'A';
            x = a[i];
            cnt--;
        }else{
            cout<<'B';
            x = b[i];
        }
    }
    cout<<endl;
}
int main(){
	daj_mi_malo_vremena
    int t; t = 1;
    while(t--){
        tc();
    }
	return 0;
}
/**
3
2 5 4 9 15 11
6 7 6 8 12 14
**/

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