Submission #954673

#	Time	Username	Problem	Language	Result	Execution time	Memory
954673		edogawa_something	Building 4 (JOI20_building4)	C++17	11 / 100	30 ms	39664 KiB

building4

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<ll> vii;
typedef pair<ll,ll> pii;
#define F first
#define S second
#define pb push_back
#define eb emplace_back
#define all(v) v.begin(),v.end()
#define pow poww
const ll M=5000;
const ll inf=2e18;
const ll mod=1e9+7;
ll pow(ll x,ll y){
  ll res=1;
  x%=mod; 
  while(y>0){
    if((y&1))
    res*=x,res%=mod;
    x*=x,x%=mod;
    y=(y>>1);
  }
  return res;
}
ll n,a[M],b[M];
bool dp[M][M][2];
int main(){
  ios_base::sync_with_stdio(0),cin.tie(0);
  int TC=1;
  //cin>>TC;
  while(TC--){
    cin>>n;
    n*=2;
    for(int i=0;i<n;i++)
    cin>>a[i];
    for(int i=0;i<n;i++)
    cin>>b[i];
    dp[0][0][0]=dp[0][1][1]=1;
    for(int i=1;i<n;i++){
      if(a[i]>=b[i-1]){
        for(int j=0;j<=i;j++){
          if(dp[i-1][j][0])
          dp[i][j+1][1]=1;
        }
      }
      if(a[i]>=a[i-1]){
        for(int j=0;j<=i;j++){
          if(dp[i-1][j][1])
          dp[i][j+1][1]=1;
        }
      }
      if(b[i]>=b[i-1]){
        for(int j=0;j<=i;j++){
          if(dp[i-1][j][0])
          dp[i][j][0]=1;
        }
      }
      if(b[i]>=a[i-1]){
        for(int j=0;j<=i;j++){
        if(dp[i-1][j][1])
        dp[i][j][0]=1;
        }
      }
    }
    ll cnt=n-1,cur=n/2;
    string ans;
    if(!dp[cnt][cur][0]&&!dp[cnt][cur][1]){
      cout<<-1;
      return 0;
    }
    bool c=0;
    if(!dp[cnt][cur][0])
    c=1;
    if(c)
    ans.pb('A'),cur--;
    else
    ans.pb('B');
    cnt--;
    while(cnt>0){
      if(c){
        if(a[cnt+1]>=b[cnt]&&dp[cnt][cur][0]){
        ans.pb('B'),c=0;
        cnt--;
        }
        else{
          ans.pb('A'),c=1;
          cnt--,cur--;
        }
      }
      else{
        if(b[cnt+1]>=b[cnt]&&dp[cnt][cur][0]){
          ans.pb('B'),c=0;
          cnt--;
        }
        else{
          ans.pb('A'),c=1;
          cnt--,cur--;
        }
      }
    }
    if(cur)
    ans.pb('A');
    else
    ans.pb('B');
    reverse(all(ans));
    cout<<ans;
  }
  return 0;
}
/*

*/  

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