Submission #1051818

#	Time	Username	Problem	Language	Result	Execution time	Memory
1051818		otarius	Alternating Current (BOI18_alternating)	C++17	0 / 100	107 ms	1372 KiB

alternating

#include <bits/stdc++.h>
#include <bits/extc++.h>
using namespace __gnu_pbds;
using namespace std;

// #pragma GCC optimize("Ofast")
// #pragma GCC optimize ("unroll-loops")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")

#define ff first
#define sc second
#define pb push_back
#define ll long long
#define pll pair<ll, ll>
#define pii pair<int, int>
#define ull unsigned long long
#define all(x) (x).begin(),(x).end()

// #define int long long
// #define int unsigned long long

// #define ordered_set(T) tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>
// #define ordered_multiset(T) tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>

void open_file(string filename) {
    freopen((filename + ".in").c_str(), "r", stdin);
    freopen((filename + ".out").c_str(), "w", stdout);
}

// const ll mod = 1e9 + 7;
// const ll mod = 998244353;

const ll inf = 1e9;
const ll biginf = 1e18;
const int maxN = 1e5 + 25;

void solve() {
    int n, m;
    cin >> n >> m;
    int a[m], b[m];
    for (int i = 0; i < m; i++)
        cin >> a[i] >> b[i];
    for (int i = 0; i < (1 << m); i++) {
        bool x[n + 1] = {}, y[n + 1] = {};
        for (int j = 0; j < m; j++) {
            if ((i >> j) & 1) {
                if (a[j] <= b[j]) {
                    for (int k = a[j]; k <= b[j]; k++) {
                        x[k] = 1;
                    }
                } else {
                    for (int k = a[j]; k <= n; k++) x[k] = 1;
                    for (int k = 1; k <= b[j]; k++) x[k] = 1;
                }
            } else {
                if (a[j] <= b[j]) {
                    for (int k = a[j]; k <= b[j]; k++) {
                        y[k] = 1;
                    }
                } else {
                    for (int k = a[j]; k <= n; k++) y[k] = 1;
                    for (int k = 1; k <= b[j]; k++) y[k] = 1;
                }
            }
        } bool f = 1;
        for (int j = 1; j <= n; j++) {
            if (!x[j] || !y[j]) f = 0;
        }
        if (f || i == 20) {
            for (int j = 0; j < m; j++) {
                cout << (i >> j) % 2;
            } return;
        }
    } cout << "impossible";
}
int32_t main() { 
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr); cout.tie(nullptr);
    
    int t = 1;
    // cin >> t;
    while (t--) {
        solve();
        cout << '\n';
    }
    return 0;
}

Compilation message (stderr)

alternating.cpp: In function 'void open_file(std::string)':
alternating.cpp:26:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   26 |     freopen((filename + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
alternating.cpp:27:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |     freopen((filename + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 13
• Subtask 2: 0 / 20
• Subtask 3: 0 / 22
• Subtask 4: 0 / 19
• Subtask 5: 0 / 26