Submission #498803

#	Time	Username	Problem	Language	Result	Execution time	Memory
498803		sidon	Dancing Elephants (IOI11_elephants)	C++17	100 / 100	3876 ms	12548 KiB

elephants

#include <bits/stdc++.h>
using namespace std;
#include "elephants.h"
 
const int MAX_N = 150'000, B = 500, INF = 2e9;
 
int N, L, LIM, X[MAX_N], Y[MAX_N], num[MAX_N], pos[MAX_N], q_;
 
vector<int> a[B], b[B];
 
void recalculate(int j) {
	auto &c = a[j];
	int sz = size(c), pt = sz;
 
	for(int i = sz; --i >= 0; ) {
		while(pt && X[c[i]] + L < X[c[pt-1]]) --pt;
 
		num[c[i]] = pt < sz ? num[c[pt]] + 1 : 1;
		pos[c[i]] = pt < sz ? pos[c[pt]] : X[c[i]] + L;
	}
}
 
void reset() {
	for(int i = 0, j = 0; i < LIM; i++) {
		for(int &v : a[i]) pos[j++] = v;
		a[i].clear();
		b[i].clear();
		if(i + 1 == LIM)
			assert(j == N);
	}
	for(int i = 0; i < N; i++) {
		Y[pos[i]] = i/B;
		a[i/B].push_back(pos[i]);
		b[i/B].push_back(X[pos[i]]);
	}
	for(int i = 0; i < LIM; i++)
		recalculate(i);
}
 
void init(int n, int l, int x[]) {
	N = n, L = l, LIM = (N - 1)/B + 1;
	for(int i = 0; i < N; i++) {
		X[i] = x[i];
		a[i/B].push_back(i);
	}
	reset();
}

int update(int i, int y) {
	int l = Y[i];
	int p = lower_bound(begin(b[l]), end(b[l]), X[i]) - begin(b[l]);
	while(a[l][p] != i) ++p;
	a[l].erase(begin(a[l]) + p);
	b[l].erase(begin(b[l]) + p);
	recalculate(l);
 
	X[i] = y;
 
	for(l = 0; l < LIM; l++)
		if(!empty(b[l]) && b[l][0] > X[i]) break;
	if(l) --l;
	p = lower_bound(begin(b[l]), end(b[l]), X[i]) - begin(b[l]);
	Y[i] = l;
	a[l].insert(begin(a[l]) + p, i);
	b[l].insert(begin(b[l]) + p, X[i]);
	recalculate(l);
 
	if(!(++q_ % (B - 2))) reset();
 
	int res = 0, curr = -1;
 
	for(int k = 0; k < LIM; k++) {
		if(empty(b[k]) || curr >= b[k].back()) continue;
 
		int j = upper_bound(begin(b[k]), end(b[k]), curr) - begin(b[k]);
 
		res += num[a[k][j]];
		curr = pos[a[k][j]];
	}
	return res;
}

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