Submission #270164

#	Time	Username	Problem	Language	Result	Execution time	Memory
270164		PeppaPig	Dancing Elephants (IOI11_elephants)	C++14	26 / 100	27 ms	3712 KiB

elephants

#include "elephants.h"
#include <bits/stdc++.h>

#define pii pair<int, int>
#define x first
#define y second

using namespace std;

const int N = 1.5e5 + 5;
const int B = 390;

int n, k;
int R[B + 1], pos[N];
map<int, int> mp;
vector<int> jump[B + 5], cnt[B + 5], bucket[B + 5];

void init(int _n, int _k, int X[]) {
    n = _n, k = _k;
    for(int i = 0; i < n; i++) ++mp[pos[i] = X[i]];
}

void solve_bucket(int idx) {
    vector<int> &vec = bucket[idx];

    jump[idx] = vector<int>(vec.size()), cnt[idx] = vector<int>(vec.size());
    for(int i = vec.size() - 1; ~i; i--) {
        int nex = upper_bound(vec.begin(), vec.end(), vec[i] + k) - vec.begin();
        if(nex >= vec.size()) jump[idx][i] = vec[i] + k, cnt[idx][i] = 1;
        else jump[idx][i] = jump[idx][nex], cnt[idx][i] = cnt[idx][nex] + 1;
    }
}

void revalidate() {
    int ptr = 0;
    for(pii p : mp) {
        if(!ptr || bucket[ptr - 1].size() >= B)
            bucket[ptr++].clear();
        bucket[ptr - 1].emplace_back(p.x);
    }
    for(int i = 0; i < B; i++) if(bucket[i].size()) {
        if(bucket[i + 1].size()) R[i] = bucket[i + 1][0];
        else R[i] = 2e9;

        solve_bucket(i);
    } 
}

void add_elephant(int x) {
    int ptr = 0;
    while(R[ptr] < x) ++ptr;
    int idx = lower_bound(bucket[ptr].begin(), bucket[ptr].end(), x) - bucket[ptr].begin();
    bucket[ptr].insert(bucket[ptr].begin() + idx, x);

    solve_bucket(ptr);
}

void del_elephant(int x) {
    int ptr = 0;
    while(R[ptr] < x) ++ptr;
    bucket[ptr].erase(lower_bound(bucket[ptr].begin(), bucket[ptr].end(), x));

    solve_bucket(ptr);
}

int counter;

int update(int i, int y) {
    if(counter++ % B == 0) revalidate();

    if(!--mp[pos[i]]) del_elephant(pos[i]);
    if(!mp[pos[i] = y]++) add_elephant(y);

    int answer = 0, cur = -1;
    for(int i = 0; i < B; i++) {
        int idx = upper_bound(bucket[i].begin(), bucket[i].end(), cur) - bucket[i].begin();
        if(idx < bucket[i].size())
            answer += cnt[i][idx], cur = jump[i][idx];
    }

    return answer;
}

Compilation message (stderr)

elephants.cpp: In function 'void solve_bucket(int)':
elephants.cpp:29:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   29 |         if(nex >= vec.size()) jump[idx][i] = vec[i] + k, cnt[idx][i] = 1;
      |            ~~~~^~~~~~~~~~~~~
elephants.cpp: In function 'int update(int, int)':
elephants.cpp:77:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   77 |         if(idx < bucket[i].size())
      |            ~~~~^~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 16 / 16
• Subtask 3: 0 / 24
• Subtask 4: 0 / 47
• Subtask 5: 0 / 3