#include<bits/stdc++.h>
using namespace std;
#define int long long
#define F first
#define S second
#define all(x) x.begin(),x.end()
#define pii pair<int,int>
#define pb push_back
#define sz(x) (int)(x.size())
#define chmin(x,y) x=min(x,y)
#define chmax(x,y) x=max(x,y)
#define vi vector<int>
#define vp vector<pii>
#define vvi vector<vi>
#define ykh mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count())
#define __lg(x) 63-__builtin_clzll(x)
#define pow2(x) (1LL<<x)
void __print(int x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifdef local
void setio(){freopen("/Users/iantsai/Library/Mobile Documents/com~apple~CloudDocs/cpp/Empty.md","r",stdin);}
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
void setio(){}
#define debug(x...)
#endif
void setIO(string s) {
freopen((s + ".in").c_str(), "r", stdin);
freopen((s + ".out").c_str(), "w", stdout);
}
struct line{
int a,b;
int operator()(const int x)const{
return a*x+b;
}
};
bool check(line l1,line l2,line l3){
return (l3.b-l2.b)*(l1.a-l2.a)<=(l2.b-l1.b)*(l2.a-l3.a);
}
const int mxn=5e5+5;
pii dp[mxn][2];
int a[mxn];
int b[mxn];
void upd(pii &a,pii b,bool tf){
a.F=min(a.F,tf+b.F);
a.S=max(a.S,tf+b.S);
}
signed main(){
setio();
ios::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
int n;
cin>>n;
for(int i=1;i<=2*n;i++){
cin>>a[i];
}
for(int i=1;i<=2*n;i++){
cin>>b[i];
}
for(int i=1;i<=2*n;i++){
for(int j=0;j<2;j++){
dp[i][j]={1e18,-1e18};
}
}
for(int i=1;i<=2*n;i++){
if(a[i-1]<=a[i])upd(dp[i][0],dp[i-1][0],1);
if(a[i-1]<=b[i])upd(dp[i][1],dp[i-1][0],0);
if(b[i-1]<=a[i])upd(dp[i][0],dp[i-1][1],1);
if(b[i-1]<=b[i])upd(dp[i][1],dp[i-1][1],0);
}
if(dp[2*n][0].F<=n and n<=dp[2*n][0].S){
vector<char>ans;
ans.pb('A');
int cur=n-1;
int prev=a[n];
for(int i=2*n;i>=2;i--){
if(cur>0 and dp[i-1][0].F<=cur and dp[i-1][0].S>=cur and a[i-1]<=prev){
ans.pb('A');
cur--;
prev=a[i-1];
}
else{
ans.pb('B');
prev=b[i-1];
}
}
reverse(all(ans));
for(auto i:ans){
cout<<i;
}
cout<<'\n';
}
else if(dp[2*n][1].F<=n and n<=dp[2*n][1].S){
vector<char>ans;
ans.pb('B');
int cur=n;
int prev=b[n];
for(int i=2*n;i>=2;i--){
if(cur>0 and dp[i-1][0].F<=cur and dp[i-1][0].S>=cur and a[i-1]<=prev){
ans.pb('A');
cur--;
prev=a[i-1];
}
else{
ans.pb('B');
prev=b[i-1];
}
}
reverse(all(ans));
for(auto i:ans){
cout<<i;
}
cout<<'\n';
}
else{
cout<<-1<<'\n';
}
}
/*
input:
*/
Compilation message
building4.cpp: In function 'void setIO(std::string)':
building4.cpp:42:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
42 | freopen((s + ".in").c_str(), "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
building4.cpp:43:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
43 | freopen((s + ".out").c_str(), "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
4444 KB |
Output is correct |
| 2 |
Correct |
1 ms |
4568 KB |
Output is correct |
| 3 |
Correct |
1 ms |
4444 KB |
Output is correct |
| 4 |
Correct |
1 ms |
4444 KB |
Output is correct |
| 5 |
Correct |
1 ms |
4444 KB |
Output is correct |
| 6 |
Correct |
1 ms |
4444 KB |
Output is correct |
| 7 |
Correct |
1 ms |
4632 KB |
Output is correct |
| 8 |
Correct |
1 ms |
4444 KB |
Output is correct |
| 9 |
Incorrect |
1 ms |
4444 KB |
Output isn't correct |
| 10 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
4444 KB |
Output is correct |
| 2 |
Correct |
1 ms |
4568 KB |
Output is correct |
| 3 |
Correct |
1 ms |
4444 KB |
Output is correct |
| 4 |
Correct |
1 ms |
4444 KB |
Output is correct |
| 5 |
Correct |
1 ms |
4444 KB |
Output is correct |
| 6 |
Correct |
1 ms |
4444 KB |
Output is correct |
| 7 |
Correct |
1 ms |
4632 KB |
Output is correct |
| 8 |
Correct |
1 ms |
4444 KB |
Output is correct |
| 9 |
Incorrect |
1 ms |
4444 KB |
Output isn't correct |
| 10 |
Halted |
0 ms |
0 KB |
- |
