Submission #436550

#	Time	Username	Problem	Language	Result	Execution time	Memory
436550		2qbingxuan	Detecting Molecules (IOI16_molecules)	C++14	100 / 100	131 ms	21172 KiB

molecules

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

using namespace std;

std::vector<int> find_subset(int l, int u, std::vector<int> w) {
    int n = w.size();
    // l / w_min
    vector<int> id(n);
    iota(id.begin(), id.end(), 0);
    if (long long sum = accumulate(w.begin(), w.end(), 0LL); l <= sum && sum <= u) {
        return id;
    }
    sort(id.begin(), id.end(), [&w](size_t a, size_t b) { return w[a] < w[b]; });
    vector<int> W(n);
    for (int i = 0; i < n; i++) W[i] = w[id[i]];
    vector<long long> pre(n+1), suf(n+2);
    for (int i = 1; i <= n; i++) pre[i] = pre[i-1] + W[i-1];
    for (int i = n; i >= 1; i--) suf[i] = suf[i+1] + W[i-1];
    long long sum = 0;
    map<long long,int> mp;
    for (int i = n; i >= 0; i--) {
        mp[suf[i+1]] = i+1;
        // minimum x s.t. x >= l - pre[i]
        auto it = mp.lower_bound(l - pre[i]);
        if (it != mp.end() && pre[i] + it->first <= u) {
            int j = it->second;
            vector<int> ans;
            for (int t = 0; t < i; t++) ans.push_back(id[t]);
            for (int t = j; t <= n; t++) ans.push_back(id[t-1]);
            return ans;
        }
    }
    return {};
}

Compilation message (stderr)

molecules.cpp: In function 'std::vector<int> find_subset(int, int, std::vector<int>)':
molecules.cpp:11:9: warning: init-statement in selection statements only available with '-std=c++17' or '-std=gnu++17'
   11 |     if (long long sum = accumulate(w.begin(), w.end(), 0LL); l <= sum && sum <= u) {
      |         ^~~~
molecules.cpp:20:15: warning: unused variable 'sum' [-Wunused-variable]
   20 |     long long sum = 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