Submission #603058

#	Time	Username	Problem	Language	Result	Execution time	Memory
603058		cheissmart	Shortcut (IOI16_shortcut)	C++14	100 / 100	1611 ms	49836 KiB

shortcut

// 花啊啊啊啊啊啊啊啊啊啊啊啊
#include "shortcut.h"
#pragma GCC optimize("O3", "no-stack-protector")
#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, N = 1e6 + 7;
const ll oo = 1e18;

void cmax(ll& a, ll b) {
    a = max(a, b);
}
void cmin(ll& a, ll b) {
    a = min(a, b);
}

ll a[N], b[N], pos[N];

ll find_shortcut(int n, vi l, vi d, int c) {
    assert(SZ(l) == n - 1);
    assert(SZ(d) == n);
    for(int i = 1; i < n; i++)
        pos[i] = l[i - 1] + pos[i - 1];
 
    for(int i = 0; i < n; i++)
        a[i] = pos[i] + d[i];
    for(int i = 0; i < n; i++)
        b[i] = pos[i] - d[i];

    vi goodi, goodj;
    for(int i = 0; i < n; i++)
        if(goodi.empty() || a[i] > a[goodi.back()])
            goodi.PB(i);
    for(int i = 0; i < n; i++) {
        while(goodj.size() && b[goodj.back()] >= b[i])
            goodj.pop_back();
        goodj.PB(i);
    }

    sort(ALL(goodi), [&] (int x, int y) {
        return b[x] < b[y];
    });
    sort(ALL(goodj), [&] (int x, int y) {
        return a[x] < a[y];
    });


    auto ok = [&] (ll k) {
        ll lb_sum = -oo, rb_sum = oo;
        ll lb_dif = -oo, rb_dif = oo;
        ll mx_aj = -oo;
        for(int i = n - 1; i >= 0; i--) {
            if(mx_aj > b[i] + k) {
                cmax(lb_sum, a[i] + mx_aj);
                cmin(rb_dif, b[i] - mx_aj);
            }
            mx_aj = max(mx_aj, a[i]);
        }

        int mn_j = INF, mn_j2 = INF;
        for(int i = SZ(goodi) - 1, j = SZ(goodj) - 1; i >= 0; i--) {
            while(j >= 0 && a[goodj[j]] > b[goodi[i]] + k) {
                if(goodj[j] < mn_j) mn_j2 = mn_j, mn_j = goodj[j];
                else mn_j2 = min(mn_j2, goodj[j]);
                mn_j = min(mn_j, goodj[j]);
                j--;
            }
            if(mn_j != INF && mn_j > goodi[i]) {
                cmin(rb_sum, b[goodi[i]] + b[mn_j]);
                cmax(lb_dif, a[goodi[i]] - b[mn_j]);
            }
            if(mn_j2 != INF && mn_j2 > goodi[i]) {
                cmin(rb_sum, b[goodi[i]] + b[mn_j2]);
                cmax(lb_dif, a[goodi[i]] - b[mn_j2]);
            }
        }
        
        lb_sum += c - k, rb_sum += k - c, lb_dif += c - k, rb_dif += k - c;
        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 + i + 1, pos + n, lb) - pos;
                if(j < n && pos[j] <= rb)
                    return true;
            }
        }
        return false;
    };
 
    ll lb = pos[n - 1] / 3, rb = 1e15;
    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: 4 / 4
• Subtask 8: 3 / 3