Submission #781086

#	Time	Username	Problem	Language	Result	Execution time	Memory
781086		Silence	Crayfish scrivener (IOI12_scrivener)	C++17	100 / 100	595 ms	89508 KiB

scrivener

const int mxn = 1e6 + 5;
const int k = 20;
int cur =0;
int par[mxn][k];
int val[mxn],depth[mxn];
void Init() {	
}

void TypeLetter(char L) {
	++cur;	
	val[cur] = L - 'a';
	depth[cur] = depth[cur - 1] + 1;
	par[cur][0] = cur - 1;
	for (int i = 1;i<k;++i){
		par[cur][i] = par[par[cur][i - 1]][i - 1];
	}
}

void UndoCommands(int U) {
	++cur;
	depth[cur] = depth[cur - U - 1];
	val[cur] = val[cur - U - 1];
	par[cur][0] = par[cur - U - 1][0];
	for (int i = 1;i<k;++i){
		par[cur][i] = par[par[cur][i - 1]][i - 1];
	}	
}

char GetLetter(int P) {
	int v = depth[cur] - P - 1;
	int pos = cur;
	for (int i = k - 1;i>=0;--i){
		if (v & (1<<i)){
			pos = par[pos][i];
		}
	}
	return char(val[pos] + 'a');
}

• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 22 / 22
• Subtask 4: 26 / 26
• Subtask 5: 40 / 40