Submission #714658

#	Time	Username	Problem	Language	Result	Execution time	Memory
714658		europium	Detecting Molecules (IOI16_molecules)	C++17	100 / 100	50 ms	5180 KiB

molecules

// accepted - 25/3/23
#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <numeric>
#include <cmath>
#include<iterator>
#include <set>
#include <map>
#include <math.h>
#include <iomanip>
#include <unordered_set>
#include <queue>
#include <climits>
#include "molecules.h"

using namespace std;
using ll = long long;

vector<ll> ps;
ll sum(int l, int r){
    return ps[r + 1] - ps[l];
}

vector<int> find_subset(int a, int b, vector<int> w) {
    int n = w.size();
    ps.resize(n + 1);

    vector<pair<int,int>> pos(n);

    for (int i = 0; i < n; i++){
        pos[i].first = w[i];
        pos[i].second = i;
    }

    sort(pos.begin(), pos.end());

    // init ps
    for (int i = 0; i < n; i++){
        ps[i + 1] = ps[i] + pos[i].first;
    }

    for (int k = 0; k < n; k++){
        // binary search for each k
        ll l = 0, r = n - k - 1, mid, wsum;

        while (l <= r) {
            mid = l + (r - l) / 2;

            wsum = sum(mid, mid + k);

            if (wsum < a) l = mid + 1;
            else if (wsum > b) r = mid - 1;
            else {
                vector<int> ans;
                for (int j = mid; j <= mid + k; j++) ans.push_back(pos[j].second);
                return ans;
            }
        }
    }

    // no answer, return empty vector
    return vector<int>(0);
}

• Subtask 1: 9 / 9
• Subtask 2: 10 / 10
• Subtask 3: 12 / 12
• Subtask 4: 15 / 15
• Subtask 5: 23 / 23
• Subtask 6: 31 / 31