Submission #810818

#	Time	Username	Problem	Language	Result	Execution time	Memory
810818		MyCode	A Difficult(y) Choice (BOI21_books)	C++17	100 / 100	213 ms	860 KiB

books

#include <bits/stdc++.h>

#include "books.h"

using namespace std;

void solve(int n, int k, long long A, int S) {
    if (S == n) {
        long long a[n + 1];
        for (int i = 1; i <= n; i++)
            a[i] = skim(i);
        long long pref[n + 1];
        pref[0] = 0;
        for (int i = 1; i <= n; i++)
            pref[i] = a[i] + pref[i - 1];
        function<long long(int, int)> sum = [&](int l, int r) {
            return pref[r] - pref[l - 1];
        };
        for (int i = 1; i <= n; i++) {
            if (sum(i, i + k - 1) >= A && sum(i, i + k - 1) <= 2 * A) {
                vector<int> ans;
                for (int j = i; j < i + k; j++)
                    ans.emplace_back(j);
                answer(ans);
                return;
            }
        };
        long long s[n + 1];
        for (int i = 1; i + k - 2 <= n; i++)
            s[i] = sum(i, i + k - 2);
        for (int i = k; i <= n; i++) {
            int l = 1, r = i - k + 1;
            while (r - l > 1) {
                int m = (l + r) >> 1;
                if (s[m] + a[i] >= A)
                    r = m;
                else
                    l = m;
            }
            int ind = -1;
            if (s[l] + a[i] >= A)ind = l;
            else if (s[r] + a[i] >= A)ind = r;
            if (ind != -1 && s[ind] + a[i] <= 2 * A) {
                vector<int> ans;
                for (int j = ind; j < ind + k - 1; j++)
                    ans.emplace_back(j);
                ans.emplace_back(i);
                answer(ans);
                return;
            }
        }
        impossible();
        return;
    }
    long long sum = 0;
    vector<pair<int, long long>> ans;
    map<int, long long> mp;
    function<long long(int)> skimm = [&](int i) {
        if (mp.find(i) != mp.end())
            return mp[i];
        long long s = skim(i);
        mp[i] = s;
        return s;
    };
    for (int i = 1; i <= k; i++) {
        long long t = skimm(i);
        sum += t;
        ans.emplace_back(i, t);
    }
    for (int j = k; j >= 1; j--) {
        if (sum >= A)break;
        int l = ans[j - 1].first, r = (j < k ? ans[j].first - 1 : n);
        long long val = ans[j - 1].second;
        long long X = skimm(r);
        if (sum + X <= 2 * A) {
            ans[j - 1].first = r;
            sum -= ans[j - 1].second;
            ans[j - 1].second = X;
            sum += ans[j - 1].second;
            continue;
        }
        while (r - l > 1) {
            int m = (l + r) / 2;
            if (sum - val + skimm(m) >= A)
                r = m;
            else
                l = m;
        }
        long long s1 = skimm(l), s2 = skimm(r);
        if (sum - val + s2 > 2 * A || sum - val + s1 >= A)
            ans[j - 1].first = l, ans[j - 1].second = s1,
            sum = sum - val + s1;
        else
            ans[j - 1].first = r, ans[j - 1].second = s2,
            sum = sum - val + s2;
    }
    if (sum > 2 * A || sum < A)
        impossible();
    else {
        vector<int> res;
        for (int i = 0; i < k; i++)
            res.emplace_back(ans[i].first);
        answer(res);
    }
}

• 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