Submission #906490

#	Time	Username	Problem	Language	Result	Execution time	Memory
906490		vjudge1	Shortcut (IOI16_shortcut)	C++17	23 / 100	2028 ms	1248 KiB

shortcut

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

#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("avx,avx2,fma")

using namespace std;

using vi = vector<int>;
using ll = long long;

ll find_shortcut(int n, vi l, vi d, int c) {
    vector<ll> sl;    
    for(int i = 0; i < n - 1; ++i) {
        sl.push_back(l[i]);
        if(i) sl[i] += sl[i - 1];
    }

    auto dist_direct = [&](int u, int v) {
        if(u > v) swap(u, v);
        if(!v) return 0ll;
        if(u) return sl[v - 1] - sl[ u - 1 ];
        else return sl[v - 1];
    };
    vector<vector<ll> > DD(n, vector(n, 0ll));
    for(int i = 0; i < n; ++i)
        for(int j = 0; j < n; ++j) DD[i][j] = dist_direct(i, j);

    auto dist = [&](int u, int v, int st, int dr) { /// (st, dr) express line
        ll re = DD[u][v];
        re = min(re, DD[u][st] + DD[dr][v] + c);
        re = min(re, DD[u][dr] + DD[st][v] + c);
        return re + d[u] + d[v];
    };
    ll re = 1e18;
    auto simu = [&](int st, int dr, ll rec) {
        ll cre = 0, ri, rj;
        for(int i = 0; i < n; ++i)
            for(int j = i + 1; j < n; ++j) {
                ll val = dist(i, j, st, dr);
                if(val > cre) {
                    ri = i;
                    rj = j;
                    cre = val;
                }
                if(cre > rec) return cre;
            }
        return cre;
    };
    vector<pair<int, int> > O;
    for(int st = 0; st < n; ++st) {
        for(int dr = st + 1; dr < n; ++dr) {
            O.push_back({st, dr});
        }
    }
    mt19937 rng(1);
    shuffle(O.begin(), O.end(), rng);
    for(auto [st, dr] : O) {
        auto cre = simu(st, dr, re);
        re = min(re, cre);
    }
    return re; 
}

Compilation message (stderr)

shortcut.cpp: In lambda function:
shortcut.cpp:37:21: warning: variable 'ri' set but not used [-Wunused-but-set-variable]
   37 |         ll cre = 0, ri, rj;
      |                     ^~
shortcut.cpp:37:25: warning: variable 'rj' set but not used [-Wunused-but-set-variable]
   37 |         ll cre = 0, ri, rj;
      |                         ^~

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