Submission #954536

#	Time	Username	Problem	Language	Result	Execution time	Memory
954536		LCJLY	Building 4 (JOI20_building4)	C++14	100 / 100	285 ms	145980 KiB

building4

#include <bits/stdc++.h>
using namespace std;
 
#define int long long 
#define ld long double
#define show(x,y) cout << y << " " << #x << endl;
#define show2(x,y,i,j) cout << y << " " << #x << "  " << j << " " << #i << endl;
#define show3(x,y,i,j,p,q) cout << y << " " << #x << "  " << j << " " << #i << "  " << q << " " << #p << endl;
#define show4(x,y) for(auto it:y) cout << it << " "; cout << #x << endl;
typedef pair<int,int>pii;
typedef pair<pii,pii>pi2;
mt19937 rng(chrono::system_clock::now().time_since_epoch().count());
 
int n;
int a[1000005];
int b[1000005];
pii memo[1000005][2];

pii dp(int index, bool amos){
	if(index>2*n){
		return memo[index][amos]={0,0};
	}
	if(memo[index][amos].first!=-1) return memo[index][amos];
	pii ans={INT_MAX,INT_MIN};
	if(amos){
		if(a[index]>=a[index-1]){
			pii hold=dp(index+1,true);
			if(hold.first<=hold.second){
				ans.first=min(ans.first,hold.first+1);
				ans.second=max(ans.second,hold.second+1);
			}
		}
		if(b[index]>=a[index-1]){
			pii hold=dp(index+1,false);
			if(hold.first<=hold.second){
				ans.first=min(ans.first,hold.first);
				ans.second=max(ans.second,hold.second);
			}
		}
	}
	else{
		if(a[index]>=b[index-1]){
			pii hold=dp(index+1,true);
			if(hold.first<=hold.second){
				ans.first=min(ans.first,hold.first+1);
				ans.second=max(ans.second,hold.second+1);
			}
		}
		if(b[index]>=b[index-1]){
			pii hold=dp(index+1,false);
			if(hold.first<=hold.second){
				ans.first=min(ans.first,hold.first);
				ans.second=max(ans.second,hold.second);
			}
		}
	}
	return memo[index][amos]=ans;
}

void dfs(int index, bool amos, int need){
	if(index>2*n) return;
	pii take={INT_MAX,INT_MIN};
	pii take2={INT_MAX,INT_MIN};
	
	if(amos){
		if(a[index]>=a[index-1]){
			take=memo[index+1][true];
			take.first++;
			take.second++;
		}
		if(b[index]>=a[index-1]){
			take2=memo[index+1][false];
		}
	}
	else{
		if(a[index]>=b[index-1]){
			take=memo[index+1][true];
			take.first++;
			take.second++;
		}
		if(b[index]>=b[index-1]){
			take2=memo[index+1][false];
		}
	}
	
	if(take.first<=need&&take.second>=need){
		cout << "A";
		dfs(index+1,true,need-1);
	}
	else{
		cout << "B";
		dfs(index+1,false,need);
	}
}
 
void solve(){
	cin >> n;
	
	for(int x=1;x<=2*n;x++){
		cin >> a[x];
	}
	
	for(int x=1;x<=2*n;x++){
		cin >> b[x];
	}
	
	memset(memo,-1,sizeof(memo));
	pii hold=dp(1,0);
	
	if(hold.first<=n&&hold.second>=n){
		dfs(1,0,n);
	}
	else{
		cout << -1;
	}
}	
 
int32_t main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	int t=1;
	//cin >> t;
	while(t--){
		solve();
	}
}

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