Submission #805510

#	Time	Username	Problem	Language	Result	Execution time	Memory
805510		QwertyPi	Dancing Elephants (IOI11_elephants)	C++14	100 / 100	8871 ms	18468 KiB

elephants

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

const int MAXN = 1.5e5 + 11;
const int SQ = 400;
int n, l;
int x[MAXN], _x[MAXN];

using namespace std;

struct naive{
    int n, y[SQ * 2 + 1], dp[SQ * 2 + 1], fin[SQ * 2 + 1];
    void build(int n, int x[]){
        naive::n = n;
        for(int i = 0; i < n; i++){
            y[i] = x[i];
        }
        precalc();
    }
    void rem(int x){
        int i; for(i = 0; i < n; i++) if(y[i] == x) break;
        for(int j = i; j < n - 1; j++) y[j] = y[j + 1];
        n--; precalc();
    }
    void add(int x){
        int i; for(i = 0; i < n; i++) if(y[i] > x) break;
        for(int j = n - 1; j >= i; j--) y[j + 1] = y[j];
        y[i] = x;
        n++; precalc();
    }
    void precalc(){
        dp[n] = 0; fin[n] = n; int r = n - 1;
        for(int j = n - 1; j >= 0; j--){
            while(y[r] - y[j] > l) r--;
            dp[j] = dp[r + 1] + 1;
            fin[j] = r + 1 != n ? fin[r + 1] : j;
        }
    }
    pair<int, int> qry(int x){
        int id = upper_bound(y, y + n, x) - y;
        if(id == n) return {0, 0};
        return {dp[id], y[fin[id]]};
    }
} cal[MAXN / SQ + 10];

int B[MAXN / SQ + 10], size_B;
unordered_map<int, int> mp;
void rebuild(){
    mp.clear(); for(int i = 0; i < n; i++) mp[_x[i]]++;
    for(int i = 0; i < n; i++) x[i] = _x[i];
    std::sort(x, x + n); int k = unique(x, x + n) - x;
    B[0] = 0;
    for(int i = 1; i < (k + SQ - 1) / SQ; i++){
        B[i] = x[SQ * i];
    }
    B[(k + SQ - 1) / SQ] = 1 << 30;
    size_B = (k + SQ - 1) / SQ;
    for(int i = 0; i < (k + SQ - 1) / SQ; i++){
        cal[i].build(min(SQ, k - i * SQ), x + i * SQ);
    }
}

void rem(int x){
    mp[x]--; if(mp[x] > 0) return;
    int id = upper_bound(B, B + size_B, x) - B - 1;
    cal[id].rem(x);
}

void add(int x){
    mp[x]++; if(mp[x] > 1) return;
    int id = upper_bound(B, B + size_B, x) - B - 1;
    cal[id].add(x);
}

int qry(){
    int ans = 0, x = -1, b = 0;
    for(int b = 0; b < size_B; b++){
        if(x >= B[b + 1]) continue;
        pair<int, int> p = cal[b].qry(x);
        ans += p.first; if(p.first != 0) x = p.second + l;
    }
    return ans;
}

void init(int N, int L, int X[]){
    n = N; l = L; for(int i = 0; i < n; i++) _x[i] = x[i] = X[i]; rebuild();
}

int uid = 0;
int update(int i, int y){
    rem(_x[i]);
    _x[i] = y;
    add(_x[i]);
    uid++; if(uid % SQ == 0) rebuild();
    return qry();
}

Compilation message (stderr)

elephants.cpp: In function 'int qry()':
elephants.cpp:76:26: warning: unused variable 'b' [-Wunused-variable]
   76 |     int ans = 0, x = -1, b = 0;
      |                          ^

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