Submission #781940

#	Time	Username	Problem	Language	Result	Execution time	Memory
781940		TheSahib	The Big Prize (IOI17_prize)	C++14	92.88 / 100	90 ms	16240 KiB

prize

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

using namespace std;

const int MAX = 2e5 + 5;

int tree[MAX];

void update(int pos, int val){
    while(pos < MAX){
        tree[pos] += val;
        pos += pos & (-pos);
    }
}

int ask(int l, int r){
    if(r < l) return 0;
    if(l != 1) return ask(1, r) - ask(1, l - 1);
    int ans = 0;
    while(r > 0){
        ans += tree[r];
        r -= r & (-r);
    }
    return ans;
}

int intRand(){
    return (rand() << 14) | rand();
}

vector<int> mp[MAX];

vector<int> query(int i){
    if(!mp[i].empty()) return mp[i];
    return mp[i] = ask(i - 1);
}


int find_best(int n) {
    vector<int> order(n);
    srand(time(0));
    iota(order.begin(), order.end(), 1);
    random_shuffle(order.begin(), order.end());
    vector<int> a;
    int cnt = 0;
    
    set<int> st;
    for (int i = 0; i < n; i++)
    {
        st.insert(i + 1);
    }
    for (int j = 0; j < min(1000, (int)order.size()); ++j)
    {
        int i = order[j];
        a = query(i);
        if(a[0] + a[1] == 0) return i - 1;
        if(a[0] + a[1] < cnt){
            update(i, 1);
            st.erase(i);

        }
        else{
            cnt = a[0] + a[1];
        }
    }
    
    
    for(int j = 0; j <= cnt; ++j){
        int l = 1, r = n;
        while(l <= r){
            int x = (l + r) / 2;
            auto itr = st.lower_bound(x);
            if(itr == st.end() || *itr > r){
                --itr;
            }
            int mid = *itr;

            a = query(mid);

            if(a[0] + a[1] == 0){
                return mid - 1;
            }
            if(a[0] + a[1] < cnt && !ask(mid, mid)){
                update(mid, 1);
                st.erase(mid);
                break;
            }
            a[0] -= ask(1, mid - 1);
            a[1] -= ask(mid + 1, n);


            if(a[1] > 0){
                l = mid + 1;
            }
            else{
                r = mid - 1;
            }
        }
    }
}

Compilation message (stderr)

prize.cpp: In function 'int find_best(int)':
prize.cpp:41:24: warning: control reaches end of non-void function [-Wreturn-type]
   41 |     vector<int> order(n);
      |                        ^

• Subtask 1: 20 / 20
• Subtask 2: 72.88 / 80