| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 1220607 | settop | Crayfish scrivener (IOI12_scrivener) | C++20 | 0 ms | 0 KiB |
#include<bits/stdc++.h>
#define eb emplace_back
#define S second
#define dbg(v) cerr << #v << " = " << v << "\n"
#define F first
#define fall(i,a,n) for(int i=a;i<=n;i++)
#define rfall(i,a,n) for(int i=a;i>=n;i--)
#define pb push_back
#define all(x) x.begin(),x.end()
#define lsb(x) (x & -x)
#define sz(x) (int)x.size()
const int MAXN=1e6+10;
const int MAXL=21;
const int inf=1e14;
const int MOD=998244353;
using namespace std;
typedef pair<int,int> pii;
typedef tuple<int,int,int> trio;
int cont=0,s=-1,op[MAXN]={-1},last=0;
int sparse[MAXN][MAXL];
set<pair<int,char>> st[MAXN];
void Init(){
return;
}
void TypeLetter(char L){
s++;
cont++;
st[s].insert({cont,L});
sparse[cont][0]=last;
fall(i,1,MAXL-1) sparse[cont][i]=sparse[sparse[cont][i-1]][i-1];
op[cont]=s;
}
void UndoCommands(int U) {
cont++;
sparse[cont][0]=cont-U-1;
fall(i,1,MAXL-1) sparse[cont][i]=sparse[sparse[cont][i-1]][i-1];
s=op[sparse[cont][0]];
op[cont]=s;
last=cont;
}
char GetLetter(int P) {
int x = cont;
for (int i = MAXL - 1; i >= 0; --i) {
if (sparse[x][i] != 0 && op[sparse[x][i]] >= P) {
x = sparse[x][i];
}
}
auto it = (--st[P].upper_bound({x, 'z'}));
return it->second;
}
int32_t main(){
Init();
int n; cin>>n;
while(n--){
char c; cin>>c;
if(c=='T'){
char a; cin>>a;
TypeLetter(a);
}
else if(c=='U'){
int x; cin>>x;
UndoCommands(x);
}
else{
int x; cin>>x;
cout<<GetLetter(x)<<"\n";;
}
}
}