Submission #1056686

#	Time	Username	Problem	Language	Result	Execution time	Memory
1056686		mc061	Longest Trip (IOI23_longesttrip)	C++17	15 / 100	10 ms	940 KiB

longesttrip

#include <bits/stdc++.h>
using namespace std;
 
vector<int> path;
vector<int> mxpath;
int n;
set<int> have;
 
const int maxN = 256;
bool connected[maxN][maxN]={};
bool ans[maxN][maxN]={};
 
bool are_connected(vector<int> A, vector<int> B);
 
void dfs(int v) {
    path.push_back(v);
    have.insert(v);
    if (path.size() == n) {
        return;
    }
    vector<int> ord(n);
    iota(ord.begin(), ord.end(), 0);
    random_shuffle(ord.begin(), ord.end());
    for (int i : ord) {
        if (!have.count(i)) {
            bool c = false;
            if (ans[v][i]) {
                c = connected[v][i];
            }
            else {
                ans[v][i] = ans[i][v] = true;
                bool x = are_connected(vector<int>{i}, vector<int>{v});
                connected[v][i] = connected[i][v] = x;
                c = x;
            }
            if (c)
                dfs(i);
        }
        if (path.size() == n) return;
    }
    if (path.size() == n) return;
    if (path.size() > mxpath.size()) {
        mxpath = path;
    }
    path.pop_back();
    have.erase(v);
}
 
vector<int> longest_trip(int N, int D) {
    for (int i = 0; i < N; ++i) {
        for (int j = 0; j < N; ++j) {
            connected[i][j] = false;
            ans[i][j] = false;
        }
    }
    n = N;
    int start = 0;
    path.clear();
    have.clear();
    vector<int> o(n);
    iota(o.begin(), o.end(), 0);
    random_shuffle(o.begin(), o.end());
    for (int i = 0; i < min(n, 50); ++i) {
        path.clear();
        have.clear();
        dfs(o[i]);
        if (path.size() == n) return path;
    }
    return mxpath.size() > path.size() ? mxpath : path;
}

Compilation message (stderr)

longesttrip.cpp: In function 'void dfs(int)':
longesttrip.cpp:18:21: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   18 |     if (path.size() == n) {
      |         ~~~~~~~~~~~~^~~~
longesttrip.cpp:39:25: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   39 |         if (path.size() == n) return;
      |             ~~~~~~~~~~~~^~~~
longesttrip.cpp:41:21: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   41 |     if (path.size() == n) return;
      |         ~~~~~~~~~~~~^~~~
longesttrip.cpp: In function 'std::vector<int> longest_trip(int, int)':
longesttrip.cpp:67:25: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   67 |         if (path.size() == n) return path;
      |             ~~~~~~~~~~~~^~~~
longesttrip.cpp:57:9: warning: unused variable 'start' [-Wunused-variable]
   57 |     int start = 0;
      |         ^~~~~

• Subtask 0: 0 / 0
• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 0 / 25
• Subtask 4: 0 / 60