Submission #998908

#	Time	Username	Problem	Language	Result	Execution time	Memory
998908		whatthemomooofun1729	Pipes (BOI13_pipes)	C++17	35 / 100	1100 ms	10200 KiB

pipes

#include <iostream>
#include <algorithm>
#include <utility>
#include <vector>
#include <stack>
#include <map>
#include <queue>
#include <set>
#include <unordered_set>
#include <unordered_map>
#include <cstring>
#include <cmath>
#include <functional>
#include <cassert>
#include <iomanip>
#include <numeric>
#include <bitset>
#include <sstream>
#include <chrono>
#include <random>

#define ff first
#define ss second
#define PB push_back
#define sz(x) int(x.size())
#define rsz resize
#define fch(xxx, yyy) for (auto xxx : yyy) // abusive notation
#define all(x) (x).begin(),(x).end()
#define eps 1e-9

// more abusive notation (use at your own risk):
//#define int ll

using namespace std;
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vi = vector<int>;
using vll = vector<ll>;

// debugging
void __print(int x) {std::cerr << x;}
void __print(ll x) {std::cerr << x;} /* remember to uncomment this when not using THE MACRO */
void __print(unsigned x) {std::cerr << x;}
void __print(ull x) {std::cerr << x;}
void __print(float x) {std::cerr << x;}
void __print(double x) {std::cerr << x;}
void __print(ld x) {std::cerr << x;}
void __print(char x) {std::cerr << '\'' << x << '\'';}
void __print(const char *x) {std::cerr << '\"' << x << '\"';}
void __print(const string& x) {std::cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
template<typename T, typename V> void __print(const pair<T, V> &x) {std::cerr << '{'; __print(x.ff); std::cerr << ", "; __print(x.ss); std::cerr << '}';}
template<typename T> void __print(const T& x) {int f = 0; std::cerr << '{'; for (auto &i: x) std::cerr << (f++ ? ", " : ""), __print(i); std::cerr << "}";}
void _print() {std::cerr << "]\n";}
template <typename T, typename... V> void _print(T t, V... v) {__print(t); if (sizeof...(v)) std::cerr << ", "; _print(v...);}
void println() {std::cerr << ">--------------------<" << endl;}
#ifndef ONLINE_JUDGE
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif

// templates
template <class T> bool ckmin(T &a, const T &b) {return b<a ? a = b, 1 : 0;}
template <class T> bool ckmax(T &a, const T &b) {return b>a ? a = b, 1 : 0;}
template <class T> using gr = greater<T>;
template <class T> using vc = vector<T>;
template <class T> using p_q = priority_queue<T>;
template <class T> using pqg = priority_queue<T, vc<T>, gr<T>>;
template <class T1, class T2> using pr = pair<T1, T2>;
mt19937_64 rng_ll(chrono::steady_clock::now().time_since_epoch().count());
int rng(int M) {return (int)(rng_ll()%M);} /*returns any random number in [0, M) */

// const variables
constexpr int INF = (int)2e9;
constexpr int MOD = 998244353;
constexpr ll LL_INF = (ll)3e18;
constexpr int mod = (int)1e9 + 7;
constexpr ll inverse = 500000004LL; // inverse of 2 modulo 1e9 + 7

void setIO(const string& str) {// fast input/output
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    if (str.empty()) return;
    freopen((str + ".in").c_str(), "r", stdin);
    freopen((str + ".out").c_str(), "w", stdout);
}

int N, M;
vc<vc<pii>> adj;
vi deg, vst, c, x;

signed main() { // TIME YOURSELF !!!
    setIO("");
    cin >> N >> M;
    adj.rsz(N+1), deg.rsz(N+1, 0), vst.rsz(N+1, 0), c.rsz(N+1), x.rsz(M);
    if (M > N) {
        cout << 0;
        return 0;
    }
    for (int i = 1; i <= N; ++i) {
        cin >> c[i];
    }
    for (int i = 0; i < M; ++i) {
        int a, b;
        cin >> a >> b;
        adj[a].PB({b, i});
        adj[b].PB({a, i});
        deg[a]++, deg[b]++;
    }
    queue<int> q;
    for (int i = 1; i <= N; ++i) {
        if (deg[i] == 1) {
            vst[i] = 1;
            q.push(i);
        }
    }
    int n = N;
    while (!q.empty()) {
        int v = q.front(); // 'tis a leaf
        q.pop();
        n--;
        fch(to, adj[v]) {
            int u = to.ff;
            if (!vst[u]) {
                x[to.ss] = c[v];
                c[v] -= x[to.ss], c[u] -= x[to.ss];
                deg[u]--;
                if (deg[u] == 1) {
                    vst[u] = 1;
                    q.push(u);
                }
            }
        }
    }
    if (n == 0) {
        for (int i = 0; i < M; ++i) {
            cout << 2 * x[i] << '\n';
        }
    } else {
        int start = -1;
        vc<pii> f(N+1);
        for (int i = 1; i <= N; ++i) {
            if (!vst[i]) {
                start = i;
                break;
            }
        }
        q.push(start);
        int vert, L = 1;
        while (!q.empty()) {
            int v = q.front();
            vert = v;
            q.pop();
            vst[v] = 1;
            fch(u, adj[v]) if (!vst[u.ff]) {
                f[v] = u;
                q.push(u.ff);
            }
        }
        fch(u, adj[vert]) {
            if (u.ff == start) f[vert] = u;
        }
        int t = f[start].ff, sum = 0, factor = 1;
        while (t != start) {
            L++;
            sum += factor * c[t];
            t = f[t].ff;
            factor *= -1;
        }
        if (L%2 == 0) {
            cout << 0;
            return 0;
        }
        sum >>= 1;
        x[f[start].ss] = sum;
        int w = sum;
        t = f[start].ff;
        while (t != start) {
            x[f[t].ss] = c[t] - w;
            t = f[t].ff;
            w = x[f[t].ss];
        }
        for (int i = 0; i < M; ++i) {
            cout << 2 * x[i] << '\n';
        }
    }
    return 0;
}

// TLE -> TRY NOT USING DEFINE INT LONG LONG
// CE -> CHECK LINE 45
// 5000 * 5000 size matrices are kinda big (potential mle)
// Do something, start simpler

Compilation message (stderr)

pipes.cpp: In function 'void setIO(const string&)':
pipes.cpp:88:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   88 |     freopen((str + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
pipes.cpp:89:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   89 |     freopen((str + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
pipes.cpp: In function 'int main()':
pipes.cpp:164:24: warning: 'vert' may be used uninitialized in this function [-Wmaybe-uninitialized]
  164 |         fch(u, adj[vert]) {
      |                        ^

• Subtask 1: 0 / 30
• Subtask 2: 35 / 70