Submission #953900

#	Time	Username	Problem	Language	Result	Execution time	Memory
953900		Dec0Dedd	A Difficult(y) Choice (BOI21_books)	C++14	100 / 100	1 ms	1108 KiB

books

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

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;

const int N = 1e5+10;
const int X = 12;

ll n, k, a, s;
bool us[N];
ll val[N];

ll ask(int x) {
    if (us[x]) return val[x];
    us[x]=true;
    return val[x]=skim(x);
}

bool check(vector<int> v) {
    ll sm=0;
    for (auto u : v) sm+=ask(u);
    return a <= sm && sm <= 2*a;
}

void solve(int _n, int _k, ll _a, int _s) {
    n=_n, k=_k, a=_a, s=_s;

    ll sm=0;
    vector<int> v;
    for (int i=1; i<k; ++i) v.push_back(i), sm+=ask(i);
    if (sm+ask(k) > 2*a) {
        impossible();
        return;
    } else if (a <= sm+ask(k) && sm+ask(k) <= 2*a) {
        v.push_back(k);
        answer(v);
        return;
    } sm+=ask(k);

    int l=k, r=n, res=l;
    while (l <= r) {
        int m=(l+r)/2;
        if (ask(m) <= a) res=m, l=m+1;
        else r=m-1;
    }

    set<int> sx;
    for (int i=1; i<=k; ++i) sx.insert(i);

    if (res+1 <= n && sm-ask(k)+ask(res+1) <= 2*a && sm-ask(k)+ask(res+1) >= a) {
        sx.erase(k), sx.insert(res+1);
        answer(vector<int>(sx.begin(), sx.end()));
        return;
    }

    int lp=k, rp=res;
    while (sm < a && lp > 0) {
        if (sm-ask(lp)+ask(rp) <= 2*a) {
            sm=sm-ask(lp)+ask(rp);
            sx.erase(lp), sx.insert(rp);
            --lp, --rp;
        } else {
            int lf=lp, rf=rp, res=lp;

            while (lf <= rf) {
                int m=(lf+rf)/2;
                if (sm-ask(lp)+ask(m) <= 2*a) res=m, lf=m+1;
                else rf=m-1;
            }

            sx.erase(lp), sx.insert(res);
            sm=sm-ask(lp)+ask(res);
            assert(a <= sm && sm <= 2*a);

            vector<int> v(sx.begin(), sx.end());
            answer(v);
        }
    } 

    if (sm >= a && sm <= 2*a) answer(vector<int>{sx.begin(), sx.end()});
    else impossible();
}

• Subtask 1: 5 / 5
• Subtask 2: 15 / 15
• Subtask 3: 10 / 10
• Subtask 4: 15 / 15
• Subtask 5: 15 / 15
• Subtask 6: 20 / 20
• Subtask 7: 20 / 20