Submission #112353

#	Time	Username	Problem	Language	Result	Execution time	Memory
112353		socho	Detecting Molecules (IOI16_molecules)	C++14	10 / 100	2 ms	384 KiB

molecules

#include "molecules.h"
#include <bits/stdc++.h>
using namespace std;

long long n, lower, upper;
vector<pair<long long, long long> > store;
long long pf[200001];

void pfcompute() {
    pf[0] = store[0].first;
    for (long long i=1; i<n; i++) {
        pf[i] = pf[i-1] + store[i].first;
    }
}

long long pfquery(long long a, long long b) {
    if (a == 0) return pf[b];
    return pf[b] - pf[a-1];
}

pair<long long, long long> solve_for(long long left) {
    //
    long long low = left;
    long long high = n;
    long long mid;
    while (low + 1 < high) {
        mid = (low + high) / 2;
        long long sumr = pfquery(left, mid);
        if (sumr > upper) {
            high = mid;
        }
        else if (sumr < lower) {
            low = mid;
        }
        else {
            return make_pair(left, mid);
        }
    }
    if (pfquery(mid, low) <= upper && pfquery(mid, low) >= lower) {
        return make_pair(mid, low);
    }
    if (high != n) {
        if (pfquery(mid, high) <= upper && pfquery(mid, high) >= lower) {
            return make_pair(mid, high);
        }
    }
    return make_pair(-1, -1);
}

vector<int> find_subset(int l, int u, vector<int> w) {

    //
    n = w.size();
    lower = l;
    upper = u;
    for (long long i=0; i<n; i++) {
        store.push_back(make_pair(w[i], i));
    }
    sort(store.begin(), store.end());
    pfcompute();
    vector<int> ind;
    for (long long leftlock=0; leftlock<n; leftlock++) {
        pair<long long, long long> res = solve_for(leftlock);
        if (res.first == -1 && res.second == -1) {
            continue;
        }
        else {
            for (long long i=res.first; i<=res.second; i++) {
                ind.push_back(store[i].second);
            }
            return ind;
        }
    }
    return ind;

}

Compilation message (stderr)

molecules.cpp: In function 'std::pair<long long int, long long int> solve_for(long long int)':
molecules.cpp:17:5: warning: 'mid' may be used uninitialized in this function [-Wmaybe-uninitialized]
     if (a == 0) return pf[b];
     ^~
molecules.cpp:25:15: note: 'mid' was declared here
     long long mid;
               ^~~

• Subtask 1: 0 / 9
• Subtask 2: 10 / 10
• Subtask 3: 0 / 12
• Subtask 4: 0 / 15
• Subtask 5: 0 / 23
• Subtask 6: 0 / 31