Submission #1054333

#	Time	Username	Problem	Language	Result	Execution time	Memory
1054333		SN0WM4N	Pipes (CEOI15_pipes)	C++14	40 / 100	958 ms	65536 KiB

pipes

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define sort undefined_function // To use stable_sort instead sort 
#define bpc __builtin_popcount
#define ull unsigned long long
#define ld double
#define ll long long
#define mp make_pair
#define F first
#define S second
 
#pragma GCC optimize("O3")
 
#ifdef LOCAL 
        #include "debug.h"
#else 
        #define dbg(...) 0
#endif
 
using namespace __gnu_pbds;
using namespace std;
 
typedef tree<long long, null_type, less_equal<long long>,
    rb_tree_tag, tree_order_statistics_node_update> Tree;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
 
const ll INF = 9223372036854775807LL;
const ll inf = 2147483647;
const ll MOD = 998244353; //[998244353, 1e9 + 7, 1e9 + 13]
const ld PI = acos(-1);
const ll NROOT = 300;
 
ll binpow(ll a, ll b, ll _MOD = -1) {
        if (_MOD == -1)
                _MOD = MOD;
        ll res = 1;
        for (; b; b /= 2, a *= a, a %= _MOD)
                if (b & 1) res *= a, res %= _MOD;
        return res;
}
 
void set_IO(string s) {
#ifndef LOCAL
        string in  = s +  ".in";
        string out = s + ".out";
        freopen(in.c_str(),  "r",  stdin);
        freopen(out.c_str(), "w", stdout);
#endif
}
 
bool dataOverflow(ll a, ll b) {return (log10(a) + log10(b) >= 18);}
ll gcd(ll a, ll b) {return b ? gcd(b, a % b) : a;}
ll lcm(ll a, ll b) {return a * b / gcd(a, b);}
ll ceil(ll a, ll b) {return (a + b - 1) / b;}
ll invmod(ll a) {return binpow(a, MOD - 2);}
 
vector<short> tin, low;
vector<vector<short>> g;
 
short timer = 0;
 
void dfs(short x, short prt = 0) {
	tin[x] = low[x] = ++timer;
	bool ok = 0;
 
	for (auto &y : g[x]) {
		if (y == prt && !ok) {
			ok = 1;
			continue;
		}
		
		if (tin[y] == 0) {
			dfs(y, x);
			low[x] = min(low[x], low[y]);
		} else {
			low[x] = min(low[x], tin[y]);
		}
 
		if (low[y] > tin[x])
			cout << x << " " << y << "\n";
	}
}
 
int32_t main() {
        ios_base::sync_with_stdio(0);
        cin.tie(0);
 
	int n, m;
	cin >> n >> m;
 
	g.resize(n + 1);
	tin.resize(n + 1);
	low.resize(n + 1);
 
	for (int i = 1; i <= m; i ++) {
		int a, b;
		cin >> a >> b;
 
		g[a].push_back(b);
		g[b].push_back(a);
	}
 
	for (int i = 1; i <= n; i ++) {
		if (tin[i] == 0) 
			dfs(i);
	}
        
	return 0;
}

Compilation message (stderr)

pipes.cpp: In function 'void set_IO(std::string)':
pipes.cpp:47:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   47 |         freopen(in.c_str(),  "r",  stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
pipes.cpp:48:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   48 |         freopen(out.c_str(), "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 10 / 10
• Subtask 5: 0 / 10
• Subtask 6: 0 / 10
• Subtask 7: 0 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 10
• Subtask 10: 0 / 10