Submission #1202966

#	Time	Username	Problem	Language	Result	Execution time	Memory
1202966		dpsaveslives	Dancing Elephants (IOI11_elephants)	C++20	100 / 100	1586 ms	14304 KiB

elephants

#include "elephants.h"
#include <bits/stdc++.h>
#define ff first
#define ss second
using namespace std;
const int MAXN = 1.5e5+10;
const int B = 400;
int N,L,Bcnt;
vector<int> pos[MAXN];
int arr[MAXN];
int in[MAXN];
vector<pair<int,int>> dp[MAXN];
void solve(int id){
    vector<int> &poss = pos[id];
    vector<pair<int,int>> &dps = dp[id];
    int sz = poss.size();
    dps.resize(sz);
    int cur = sz;
    for(int i = sz-1;i>=0;--i){
        while(poss[cur-1] > poss[i]+L) --cur;
        if(cur == sz){
            dps[i].ff = 1;
            dps[i].ss = poss[i];
        }
        else{
            dps[i].ff = dps[cur].ff+1;
            dps[i].ss = dps[cur].ss;
        }
    }
}
int query(){
    int ans = dp[0][0].ff, lst = dp[0][0].ss;
    for(int i = 1;i<Bcnt;++i){
        if(pos[i].back() > lst+L){
            int it = upper_bound(pos[i].begin(),pos[i].end(),lst+L)-pos[i].begin();
            ans += dp[i][it].ff; lst = dp[i][it].ss;
        }
    }
    //cout << dp[0][0].ff << "\n";
    return ans;
}
void unite(){
    for(int i = 0;i<Bcnt-1;++i){
        if(pos[i].size()+pos[i+1].size() < 2*B){
            pos[i].insert(pos[i].end(),pos[i+1].begin(),pos[i+1].end());
            pos[i+1].clear(); dp[i+1].clear();
            for(int j = i+2;j<Bcnt;++j){
                swap(pos[j-1],pos[j]);
                swap(dp[j-1],dp[j]);
            }
            --Bcnt;
            solve(i);
            unite();
            return;
        }
    }
}
void del(int tar){
    int id = 0;
    while(pos[id].back() < tar){
        ++id;
    }
    pos[id].erase(lower_bound(pos[id].begin(),pos[id].end(),tar));
    if(pos[id].empty()){
        for(int i = id+1;i<Bcnt;++i){
            swap(pos[i-1],pos[i]);
            swap(dp[i-1],dp[i]);
        }
        --Bcnt;
    }
    else{
        solve(id);
    }
    unite();
}
void upd(int tar){
    int id = 0;
    while(id < Bcnt-1 && pos[id].back() < tar) ++id;
    pos[id].insert(upper_bound(pos[id].begin(),pos[id].end(),tar),tar);
    /*for(auto x : pos[id]){
        cout << x << " ";
    }
    cout << "\n";*/
    if(pos[id].size() == 2*B){
        for(int i = Bcnt-1;i>id;--i){
            swap(pos[i+1],pos[i]);
            swap(dp[i+1],dp[i]);
        }
        pos[id+1].insert(pos[id+1].begin(),pos[id].begin()+B,pos[id].end());
        pos[id].erase(pos[id].begin()+B,pos[id].end());
        ++Bcnt;
        solve(id); solve(id+1);
    }
    else{
        solve(id);
    }
    unite();
}
void init(int n,int l, int X[]){
    N = n; L = l;
    Bcnt = (N-1)/B+1;
    for(int i = 0;i<N;++i){
        arr[i] = X[i];
        pos[i/B].push_back(arr[i]);
    }
    for(int i = 0;i<Bcnt;++i){
        solve(i);
    }
}
int update(int i, int val){
    del(arr[i]);
    arr[i] = val;
    upd(val);
    int ans = query();
    return ans;
}

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