Submission #58482

#	Time	Username	Problem	Language	Result	Execution time	Memory
58482		ngkan146	Dancing Elephants (IOI11_elephants)	C++11	100 / 100	7621 ms	13124 KiB

elephants

#include "elephants.h"
#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> ii;
const int maxBlockLen = 700;
int n, length;

int numBlock;
int block[400][2000], blockSz[2000];
int bFind(int id,int val){
	for(int i=0;;i++)
		if (block[id][i] == val)	return i;
}
void bInsert(int id,int pos,int val){
	for(int i=blockSz[id];i>pos;i--)
		block[id][i] = block[id][i-1];
	block[id][pos] = val;
	blockSz[id] ++;
}
void bErase(int id,int pos){
	blockSz[id] --;
	for(int i=pos;i<blockSz[id];i++)
		block[id][i] = block[id][i+1];
}
ii startFromThis[400][2000];	// [blockId][position] = {last position, how many jumps}

int elephantPos[150005], elephantBLock[150005];

void reBuild(int blockId){
	//~ sort(block[blockId].begin(), block[blockId].end());
	// assuming sorted
	
	int nextPos = blockSz[blockId];
	for(int i = blockSz[blockId]-1;i >= 0; i--){
		while(nextPos > 0 && block[blockId][nextPos-1] > block[blockId][i] + length)
			-- nextPos;
			
		if (nextPos == blockSz[blockId])
			startFromThis[blockId][i] = {block[blockId][i], 0};
		else
			startFromThis[blockId][i] = startFromThis[blockId][nextPos],
			startFromThis[blockId][i].second ++;
	}
}

int lst[150005];
void reBuildFull(){
	for(int i=1;i<=numBlock;i++)	blockSz[i] = 0;
	numBlock = 1;
	for(int i=0;i<n;i++)	lst[i] = i;
	
	sort(lst, lst+n, [&](int x,int y){
		return elephantPos[x] < elephantPos[y];
	});
	
	for(int i=0;i<n;i++){
		if (blockSz[numBlock] == maxBlockLen)
			++ numBlock;
			
		block[numBlock][blockSz[numBlock]++] = elephantPos[lst[i]];
		elephantBLock[lst[i]] = numBlock;
	}
	
	for(int i=1;i<=numBlock;i++){
		reBuild(i);
	}
}

int cntUpdTimes;
int update(int elephantId, int newPos){
	if (++cntUpdTimes % 650 == 0)
		reBuildFull();
	//~ cout << "turn " << cntUpdTimes << endl;
	
	bErase(elephantBLock[elephantId], 
		   bFind(elephantBLock[elephantId], elephantPos[elephantId]));
		
	reBuild(elephantBLock[elephantId]);
	
	elephantPos[elephantId] = newPos;
	for(int i=1;i<=numBlock;i++){
		if (i == numBlock || newPos <= block[i][blockSz[i]-1]){
			// block[i].empty() only occur when i = numBlock
			
			elephantBLock[elephantId] = i;
			
			for(int j=0;j<=blockSz[i];j++){
				if (j == blockSz[i] || newPos <= block[i][j]){
					bInsert(i, j, newPos);
					break;
				}
			}
			
			reBuild(i);
			break;
		}
	}
	
	// find res
	int res = 0;
	int last = (int)-(1e9+5);
	for(int i=1;i<=numBlock;i++){
		int startHere = upper_bound(block[i], block[i]+blockSz[i], last + length) - block[i];
		if (startHere == blockSz[i])	continue;
		res += startFromThis[i][startHere].second + 1;
		last = startFromThis[i][startHere].first;
	}
	return res;
}

void init(int N, int L, int X[]){
	n = N;
	length = L;
	for(int i=0;i<N;i++){
		elephantPos[i] = X[i];
	}
	reBuildFull();
}

• Subtask 1: 10 / 10
• Subtask 2: 16 / 16
• Subtask 3: 24 / 24
• Subtask 4: 47 / 47
• Subtask 5: 3 / 3