Submission #7280

#	Time	Username	Problem	Language	Result	Execution time	Memory
7280		kriii	Crayfish scrivener (IOI12_scrivener)	C++98	100 / 100	612 ms	176648 KiB

scrivener

#include <vector>
#include <map>
using namespace std;

map<char, int> trie[1000001]; int prv[1000001][20];
int node,now,time,hist[1000001],len[1000001]; char last[10000001];

void Init() {}

void TypeLetter(char L) {
	int &n = trie[now][L];
	if (n == 0){
		n = ++node;
		prv[n][0] = now;
		for (int i=1;i<20;i++){
			prv[n][i] = prv[prv[n][i-1]][i-1];
			if (!prv[n][i]) break;
		}
		len[n] = len[now] + 1;
		last[n] = L;
	}
	hist[++time] = now = n;
}

void UndoCommands(int U) {
	now = hist[time-U];
	hist[++time] = now;
}

char GetLetter(int P) {
	int x = now; P = len[x] - P - 1;
	for (int i=0;i<20;i++) if (P & (1 << i)) x = prv[x][i];
	return last[x];
}

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