Submission #666741

#	Time	Username	Problem	Language	Result	Execution time	Memory
666741		1bin	Dancing Elephants (IOI11_elephants)	C++14	50 / 100	745 ms	5136 KiB

elephants

#include <bits/stdc++.h>
#include "elephants.h"
 
using namespace std;
 
#define all(v) v.begin(), v.end()
typedef long long ll;
const int NMAX = 2e5 + 5;
const int b = 400;
int n, l, m, X[NMAX], q, cnt[NMAX], d[NMAX];
vector<pair<int, int>> v[b];
 
void init(int n_, int l_, int X_[]){
    n = n_; l = l_;
    for(int i = 0; i < n; i++) {
        X[i] = X_[i];
        v[0].emplace_back(X[i], i);
    }
    sort(all(v[0]));
    return;
}
 
void go(int k){
    if(v[k].empty()) return;
    int sz = v[k].size();
    int ii = sz;
    
    for(int i = sz - 1; i >= 0; i--){
        auto&[x, ix] = v[k][i];
        while(v[k][ii - 1].first - x > l) ii--;
        if(ii == sz){
            cnt[ix] = 1; 
            d[ix] = x + l;
        }
        else {
            int p = v[k][ii].second;
            cnt[ix] = cnt[p] + 1;
            d[ix] = d[p];
        }
    }
    return;
}
 
void build(){
    vector<pair<int, int>> t;
    for(int i = 0; i < b; i++){
        for(auto& p : v[i]) t.emplace_back(p);
        v[i].clear();
    }
    for(int i = 0; i < n; i++) v[i / b].emplace_back(t[i]);
    for(int i = 0; i < b; i++) go(i);
    return;
}
 
int find(int x){
    int ret = 0;
    for(int i = 0; i < b; i++)
        if(v[i].size() && (v[i][0].first < X[x] || v[i][0].first == X[x] && v[i][0].second <= X[x])) ret = i;
    return ret;
}
 
int update(int i, int y){
    if(q++ % b == 0) build();
    int k = find(i);
    v[k].erase(lower_bound(all(v[k]), make_pair(X[i], i)));
    go(k);
    
    X[i] = y;
    k = find(i);
    auto it = lower_bound(all(v[k]), make_pair(X[i], i));
    if(it == v[k].end()) v[k].emplace_back(X[i], i);
    else v[k].insert(it, {X[i], i});
    go(k);
    
    //cout << "turns is " << q << '\n';
    //for(auto&[x, ix] : v[0]) cout << x <<  ' ';
    //cout << '\n';
    int ans = 0, e = -2;
    for(int i = 0; i < b; i++){
        auto it = lower_bound(all(v[i]), make_pair(e + 1, 0));
        if(it != v[i].end()){
            auto&[x, ix] = *it;
            ans += cnt[ix]; e = d[ix];
            //cout << ix << ' ' << cnt[ix] << ' ' << d[ix] << '\n';
        }
    }
    return ans;
}
 
/*
int main(void){
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    
    cin >> n >> l >> m;
    for(int i = 0; i < n; i++) cin >> X[i];
    init(n, l, X);
    while(m--){
        int i, y;
        cin >> i >> y;
        cout << update(i, y) << '\n';
    }
    return 0;
}
*/

Compilation message (stderr)

elephants.cpp: In function 'void go(int)':
elephants.cpp:29:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   29 |         auto&[x, ix] = v[k][i];
      |              ^
elephants.cpp: In function 'int find(int)':
elephants.cpp:58:74: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   58 |         if(v[i].size() && (v[i][0].first < X[x] || v[i][0].first == X[x] && v[i][0].second <= X[x])) ret = i;
elephants.cpp: In function 'int update(int, int)':
elephants.cpp:82:18: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   82 |             auto&[x, ix] = *it;
      |                  ^

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