Submission #600672

#	Time	Username	Problem	Language	Result	Execution time	Memory
600672		cheissmart	Shortcut (IOI16_shortcut)	C++14	93 / 100	2073 ms	23692 KiB

shortcut

// 花啊啊啊啊啊啊啊啊啊啊啊啊
#include "shortcut.h"
#include <bits/stdc++.h>
#define IO_OP std::ios::sync_with_stdio(0); std::cin.tie(0);
#define F first
#define S second
#define V vector
#define PB push_back
#define EB emplace_back
#define MP make_pair
#define SZ(v) int((v).size())
#define ALL(v) (v).begin(), (v).end()
 
using namespace std;
 
typedef long long ll;
typedef pair<int, int> pi;
typedef V<int> vi;
 
const int INF = 1e9 + 7;
const ll oo = 1e18;
 
ll find_shortcut(int n, vi l, vi d, int c) {
    assert(SZ(l) == n - 1);
    assert(SZ(d) == n);
    V<ll> pos(n);
    for(int i = 1; i < n; i++)
        pos[i] = l[i - 1] + pos[i - 1];
 
    auto ok = [&] (ll k) {
        V<pair<ll, int>> a(n), b(n);
        for(int i = 0; i < n; i++) {
            a[i] = {pos[i] + d[i], i};
            b[i] = {k + pos[i] - d[i], i};
        }
        ll lb_sum = -oo, rb_sum = oo;
        ll lb_dif = -oo, rb_dif = oo;
        auto add_condition = [&] (int i, int j) {
            // assert(i < j && pos[j] - pos[i] + d[i] + d[j] > k);
            ll dd = k - (0LL + d[i] + d[j] + c);
            lb_sum = max(lb_sum, pos[i] + pos[j] - dd);
            rb_sum = min(rb_sum, pos[i] + pos[j] + dd);
            lb_dif = max(lb_dif, pos[i] - pos[j] - dd);
            rb_dif = min(rb_dif, pos[i] - pos[j] + dd);
        };
        function<void(int, int)> cdq = [&] (int l, int r) {
            if(r - l == 1) return;
            int m = (l + r) / 2;
            cdq(l, m), cdq(m, r);
            int mxj = -1, mnj = -1;
            for(int i = m - 1, j = r - 1; i >= l; i--) {
                while(j >= m && a[j].F > b[i].F) {
                    int jj = a[j].S;
                    if(mxj == -1 || pos[jj] + d[jj] > pos[mxj] + d[mxj])
                        mxj = jj;
                    if(mnj == -1 || pos[jj] - d[jj] < pos[mnj] - d[mnj])
                        mnj = jj;
                    j--;
                }
                if(mxj != -1) add_condition(b[i].S, mxj);
                if(mnj != -1) add_condition(b[i].S, mnj);
            }
            inplace_merge(a.begin() + l, a.begin() + m, a.begin() + r);
            inplace_merge(b.begin() + l, b.begin() + m, b.begin() + r);
        };
        cdq(0, n);
        if(lb_sum > rb_sum) return false;
        if(lb_dif > rb_dif) return false;
        for(int i = 0; i < n - 1; i++) {
            ll lb = max(lb_sum - pos[i], pos[i] - rb_dif), rb = min(rb_sum - pos[i], pos[i] - lb_dif);
            if(lb <= rb) {
                int j = lower_bound(pos.begin() + i + 1, pos.end(), lb) - pos.begin();
                if(j < n && pos[j] <= rb) {
                    // assert(lb_sum <= pos[i] + pos[j] && pos[i] + pos[j] <= rb_sum);
                    // assert(lb_dif <= pos[i] - pos[j] && pos[i] - pos[j] <= rb_dif);
                    return true;
                }
            }
        }
        return false;
    };
 
    ll lb = pos[n - 1] / 3, rb = 6e13;
    while(lb <= rb) {
        ll mb = (lb + rb) / 2;
        if(ok(mb)) rb = mb - 1;
        else lb = mb + 1;
    }
    return lb;
}

• Subtask 1: 9 / 9
• Subtask 2: 14 / 14
• Subtask 3: 8 / 8
• Subtask 4: 7 / 7
• Subtask 5: 33 / 33
• Subtask 6: 22 / 22
• Subtask 7: 0 / 4
• Subtask 8: 0 / 3