Submission #1278146

#	Time	Username	Problem	Language	Result	Execution time	Memory
1278146		longdeptrai	Building 4 (JOI20_building4)	C++20	0 / 100	18 ms	31952 KiB

building4

#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
//using namespace __gnu_pbds;
#define LongDepTrai "building4"
#define ll long long
#define ull unsigned long long
#define ld long double
#define ii pair<int,int>
#define iii pair<int,ii>
#define iv pair<ii,ii>
#define pll pair<ll,ll>
#define vi vector<int>
#define vii vector<ii>
#define vll vector<ll>
#define fi first
#define se second
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define sz(x) int((x).size())
#define order_set(T) tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>

inline ll add(ll a, ll b, ll mod){ a += b; if(a >= mod) a -= mod; return a; }
inline ll sub(ll a, ll b, ll mod){ a -= b; if(a < 0) a += mod; return a; }
inline ll mul(ll a, ll b, ll mod){ return ( (ll)a * b ) % mod; }

static mt19937_64 rng((unsigned)chrono::steady_clock::now().time_since_epoch().count());
const int N=5e5+9;
const int D=2e3;
int n,a[N],b[N],f[2*2009][2009];
ii trace[2*2009][2009];
//f[i][j]:gia tri cuoi cung min de chon duoc j A tu 1->i.
//f[i][j]:
//      + chon A:if(a[i]>=f[i-1][j-1]) f[i][j]=min(f[i-1][j],a[i]);
//      + chon B:if(b[i]>=f[i-1][j])   f[i][j]=min(f[i][j],b[i]);
//
string s;
void Re(ii x){
    if(x.fi==0) return;
    cout<<x.fi<<" "<<x.se<<"\n";
    if(trace[x.fi][x.se].se==x.se) s.pb('B');
    else                           s.pb('A');
    Re(trace[x.fi][x.se]);
}
signed main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);

    if(fopen(LongDepTrai".inp","r")){
        freopen(LongDepTrai".inp","r",stdin);
        freopen(LongDepTrai".out","w",stdout);
    }
    cin>>n;
    for(int i=1;i<=2*n;i++){
        cin>>a[i];
    }
    for(int i=1;i<=2*n;i++){
        cin>>b[i];
    }
    memset(f,0x3f,sizeof(f));
    f[0][0]=0;
    trace[0][0].se=-1;
    for(int i=1;i<=2*n;i++){
        for(int j=0;j<=n;j++){
            if(j>0)
            if(a[i]>=f[i-1][j-1] && f[i][j]>a[i]){
                f[i][j]=a[i];
                trace[i][j]={i-1,j-1};
            }
            if(b[i]>=f[i-1][j] && f[i][j]>b[i]){
                f[i][j]=b[i];
                trace[i][j]={i-1,j};
            }
        }
    }
    if(trace[2*n][n].se==n) s.pb('B');
    else                    s.pb('A');
    Re(trace[2*n][n]);
    reverse(s.begin(),s.end());
    if(s.size()<2*n)
        cout<<-1;
    else
    cout<<s;
    return 0;
}

Compilation message (stderr)

building4.cpp: In function 'int main()':
building4.cpp:51:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   51 |         freopen(LongDepTrai".inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
building4.cpp:52:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   52 |         freopen(LongDepTrai".out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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