Submission #1052002

#	Time	Username	Problem	Language	Result	Execution time	Memory
1052002		otarius	Alternating Current (BOI18_alternating)	C++17	19 / 100	26 ms	3272 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;
    pair<pii, int> v[m];
    for (int i = 0; i < m; i++) {
        cin >> v[i].ff.ff >> v[i].ff.sc; v[i].sc = i;
    } int ans[m];
    sort(v, v + m);
    int a = 0, b = 0;
    for (int i = 0; i < m; i++) {
        if (a < b) {
            if (a + 1 < v[i].ff.ff) {
                cout << "impossible"; return;
            } a = max(a, v[i].ff.sc); ans[v[i].sc] = 0;
        } else {
            if (b + 1 < v[i].ff.ff) {
                cout << "impossible"; return;
            } b = max(b, v[i].ff.sc); ans[v[i].sc] = 1;
        }
    } if (a != n || b != n) {
        cout << "impossible"; return;
    } for (int i = 0; i < m; i++)
        cout << ans[i];
}
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: 19 / 19
• Subtask 5: 0 / 26