Submission #1069766

#	Time	Username	Problem	Language	Result	Execution time	Memory
1069766		mc061	Shortcut (IOI16_shortcut)	C++14	0 / 100	0 ms	348 KiB

shortcut

#pragma once
#include <bits/stdc++.h>
using namespace std;

template<typename T>
using minheap = priority_queue<T, vector<T>, greater<T>>;

const int64_t INF = 1e18;

pair<int64_t, int> get_dists(const vector<vector<pair<int, int>>>& graph, int n, int s=0) {
    vector<int64_t> d(n, INF);
    d[s] = 0;
    minheap<pair<int64_t, int>> q;
    q.push({0, s});
    while (!q.empty()) {
        pair<int64_t, int> vv = q.top();
        int v = vv.second;
        q.pop();
        for (int i = 0; i < graph[v].size(); ++i) {
            pair<int, int> uu = graph[v][i];
            int u = uu.first;
            int w = uu.second;
            if (d[u] > d[v] + w) {
                d[u] = d[v] + w;
                q.push({d[u], u});
            }
        }
    }
    pair<int64_t, int> ret = {-1e18, 69420123};
    for (int i = 0; i < n; ++i) {
        ret = max(ret, {d[i], i});
    }
    return ret;
}

long long find_shortcut(int n, vector<int> l, vector<int> d, int c) {
    vector<vector<pair<int, int>>> graph(2*n);
    for (int i = 0; i+1 < n; ++i) {
        graph[i].push_back({i+1, l[i]});
        graph[i+1].push_back({i, l[i]});
    }
    int sz = n;
    for (int i = 0; i < n; ++i) {
        if (d[i] > 0) {
            graph[i].push_back({sz, d[i]}), graph[sz].push_back({i, d[i]});
            sz++;
        }
    }
    int64_t res = 1e18;
    for (int i = 0; i < n; ++i) {
        for (int j = i+1; j < n; ++j) {
            graph[i].push_back({j, c});
            graph[j].push_back({i, c});
            int64_t diam = 0;
            auto x = get_dists(graph, 2*n, 0);
            auto y = get_dists(graph, 2*n, x.second).first;
            res = min(res, y);
            graph[i].pop_back();
            graph[j].pop_back();
        }
    }
    return res;
}

Compilation message (stderr)

shortcut.cpp:1:9: warning: #pragma once in main file
    1 | #pragma once
      |         ^~~~
shortcut.cpp: In function 'std::pair<long int, int> get_dists(const std::vector<std::vector<std::pair<int, int> > >&, int, int)':
shortcut.cpp:19:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   19 |         for (int i = 0; i < graph[v].size(); ++i) {
      |                         ~~^~~~~~~~~~~~~~~~~
shortcut.cpp: In function 'long long int find_shortcut(int, std::vector<int>, std::vector<int>, int)':
shortcut.cpp:54:21: warning: unused variable 'diam' [-Wunused-variable]
   54 |             int64_t diam = 0;
      |                     ^~~~

• Subtask 1: 0 / 9
• Subtask 2: 0 / 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