Submission #256333

#	Time	Username	Problem	Language	Result	Execution time	Memory
256333		rqi	Pipes (CEOI15_pipes)	C++14	100 / 100	1449 ms	12804 KiB

pipes

#include <bits/stdc++.h>
using namespace std;
 
typedef long long ll;
typedef long double ld;
typedef double db; 
typedef string str; 
 
typedef pair<int,int> pi;
typedef pair<ll,ll> pl; 
typedef pair<db,db> pd; 
 
typedef vector<int> vi; 
typedef vector<ll> vl; 
typedef vector<db> vd; 
typedef vector<str> vs; 
typedef vector<pi> vpi;
typedef vector<pl> vpl; 
typedef vector<pd> vpd; 
 
#define mp make_pair
#define f first
#define s second
#define sz(x) (int)x.size()
#define all(x) begin(x), end(x)
#define rall(x) (x).rbegin(), (x).rend() 
#define rsz resize
#define ins insert 
#define ft front() 
#define bk back()
#define pf push_front 
#define pb push_back
#define eb emplace_back 
#define lb lower_bound 
#define ub upper_bound 
 
#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define trav(a,x) for (auto& a: x)
 
const int MOD = 1e9+7; // 998244353;
const int MX = 2e5+5; 
const ll INF = 1e18; 
const ld PI = acos((ld)-1);
const int xd[4] = {1,0,-1,0}, yd[4] = {0,1,0,-1}; 
mt19937 rng((uint32_t)chrono::steady_clock::now().time_since_epoch().count()); 
 
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 a < b ? a = b, 1 : 0; } 
int pct(int x) { return __builtin_popcount(x); } 
int bits(int x) { return 31-__builtin_clz(x); } // floor(log2(x)) 
int cdiv(int a, int b) { return a/b+!(a<0||a%b == 0); } // division of a by b rounded up, assumes b > 0 
int fstTrue(function<bool(int)> f, int lo, int hi) {
    hi ++; assert(lo <= hi); // assuming f is increasing
    while (lo < hi) { // find first index such that f is true 
        int mid = (lo+hi)/2; 
        f(mid) ? hi = mid : lo = mid+1; 
    } 
    return lo;
}
 
// INPUT
template<class A> void re(complex<A>& c);
template<class A, class B> void re(pair<A,B>& p);
template<class A> void re(vector<A>& v);
template<class A, size_t SZ> void re(array<A,SZ>& a);
 
template<class T> void re(T& x) { cin >> x; }
void re(db& d) { str t; re(t); d = stod(t); }
void re(ld& d) { str t; re(t); d = stold(t); }
template<class H, class... T> void re(H& h, T&... t) { re(h); re(t...); }
 
template<class A> void re(complex<A>& c) { A a,b; re(a,b); c = {a,b}; }
template<class A, class B> void re(pair<A,B>& p) { re(p.f,p.s); }
template<class A> void re(vector<A>& x) { trav(a,x) re(a); }
template<class A, size_t SZ> void re(array<A,SZ>& x) { trav(a,x) re(a); }
 
// TO_STRING
#define ts to_string
str ts(char c) { return str(1,c); }
str ts(bool b) { return b ? "true" : "false"; }
str ts(const char* s) { return (str)s; }
str ts(str s) { return s; }
template<class A> str ts(complex<A> c) { 
    stringstream ss; ss << c; return ss.str(); }
str ts(vector<bool> v) { 
    str res = "{"; F0R(i,sz(v)) res += char('0'+v[i]);
    res += "}"; return res; }
template<size_t SZ> str ts(bitset<SZ> b) {
    str res = ""; F0R(i,SZ) res += char('0'+b[i]);
    return res; }
template<class A, class B> str ts(pair<A,B> p);
template<class T> str ts(T v) { // containers with begin(), end()
    bool fst = 1; str res = "{";
    for (const auto& x: v) {
        if (!fst) res += ", ";
        fst = 0; res += ts(x);
    }
    res += "}"; return res;
}
template<class A, class B> str ts(pair<A,B> p) {
    return "("+ts(p.f)+", "+ts(p.s)+")"; }
 
// OUTPUT
template<class A> void pr(A x) { cout << ts(x); }
template<class H, class... T> void pr(const H& h, const T&... t) { 
    pr(h); pr(t...); }
void ps() { pr("\n"); } // print w/ spaces
template<class H, class... T> void ps(const H& h, const T&... t) { 
    pr(h); if (sizeof...(t)) pr(" "); ps(t...); }
 
// DEBUG
void DBG() { cerr << "]" << endl; }
template<class H, class... T> void DBG(H h, T... t) {
    cerr << ts(h); if (sizeof...(t)) cerr << ", ";
    DBG(t...); }
#ifdef LOCAL // compile with -DLOCAL
#define dbg(...) cerr << "LINE(" << __LINE__ << ") -> [" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
#else
#define dbg(...) 0
#endif
 
// FILE I/O
void setIn(string s) { freopen(s.c_str(),"r",stdin); }
void setOut(string s) { freopen(s.c_str(),"w",stdout); }
void unsyncIO() { ios_base::sync_with_stdio(0); cin.tie(0); }
void setIO(string s = "") {
    unsyncIO();
    // cin.exceptions(cin.failbit); 
    // throws exception when do smth illegal
    // ex. try to read letter into int
    if (sz(s)) { setIn(s+".in"), setOut(s+".out"); } // for USACO
}
 
/**
 * Description: Disjoint Set Union with path compression
     * and union by size. Add edges and test connectivity. 
     * Use for Kruskal's or Boruvka's minimum spanning tree.
 * Time: O(\alpha(N))
 * Source: CSAcademy, KACTL
 * Verification: USACO superbull
 */
 
struct DSU {
    vi e; void init(int n) { e = vi(n,-1); }
    int get(int x) { return e[x] < 0 ? x : e[x] = get(e[x]); } 
    bool sameSet(int a, int b) { return get(a) == get(b); }
    int size(int x) { return -e[get(x)]; }
    bool unite(int x, int y) { // union by size
        x = get(x), y = get(y); if (x == y) return 0;
        if (e[x] > e[y]) swap(x,y);
        e[x] += e[y]; e[y] = x; return 1;
    }
};
 
vector<vi> adj; //may not be connected
vi q; //query number for each node
vi qnum; //# left for each query number
vector<vi> qlist; //nodes for each query number
vi num; //-sz at each lca
vpi ans;
 
struct LCAOff {
    vi e; //-index of highest node in component
    vi depth;
    int get(int x) { return e[x] < 0 ? x : e[x] = get(e[x]); } 
    bool sameSet(int a, int b) { return get(a) == get(b); }
    int tope(int x) { return -e[get(x)]; }
    bool unite(int x, int y) { // union by size, node, parent
        x = get(x), y = get(y); 
        if (x == y) return 0;
        int hi = e[y];
        if (e[x] > e[y]) swap(x,y);
        e[x] += e[y]; e[y] = x; 
        e[x] = hi;
        return 1;
    }
 
    void dfs(int node, int prv = -1){
        if(prv == -1){
            depth[node] = 0;
        }
        else{
            depth[node] = depth[prv]+1;
        }
        qnum[q[node]]--;
        if(qnum[q[node]] == 0){ //process query
            int hi = node;
            int curd = depth[node];
            for(auto u: qlist[q[node]]){
                if(depth[tope(u)] < curd){
                    hi = tope(u);
                    curd = depth[hi];
                }
            }
            num[hi]-=sz(qlist[q[node]]);
        }
 
        for(auto u: adj[node]){
            if(u == prv) continue;
            dfs(u, node);
        }
 
        if(prv != -1) unite(node, prv);
    }
 
    void prop(int node, int prv = -1){
        for(auto u: adj[node]){
            if(u == prv) continue;
            prop(u, node);
            num[node]+=num[u];
        }
        if(prv != -1 && num[node] == 0){
            ans.pb(mp(node, prv));
        }
    }
 
    void init(int n) { 
        e = vi(n+1,-1); 
        depth = vi(n+1, -1);
        for(int i = 1; i <= n; i++){
            e[i] = -i;
            num[i]++;
        }
        for(int i = 1; i <= n; i++){
            if(depth[i] != -1) continue;
            dfs(i);
            prop(i);
        }
    }
    
};
 
DSU span; //use to get tree span edges
DSU ext; //use to get q
LCAOff gen;
 
int main() {
    setIO();
    int N, M;
    cin >> N >> M;
    span.init(N+1);
    ext.init(N+1);
    
    for(int i = 0; i <= N; i++){
        adj.pb(vi{});
    }
    for(int i = 1; i <= M; i++){
        int u, v;
        cin >> u >> v;
        if(span.unite(u, v)){
            adj[u].pb(v);
            adj[v].pb(u);
        }
        else{
            ext.unite(u, v);
        }
    }
    span.e.clear();
    q = vi(N+1, 0);
    qnum = vi(N+1, 0);
    for(int i = 0; i <= N; i++){
        qlist.pb(vi{});
    }
    num = vi(N+1, 0);
 
    for(int i = 1; i <= N; i++){
        q[i] = ext.get(i);
        qnum[q[i]]++;
        qlist[q[i]].pb(i);
    }

    ext.e.clear();
 
    gen.init(N);
 
    for(auto u: ans){
        ps(u.f, u.s);
    }
    // you should actually read the stuff at the bottom
}
 
/* stuff you should look for
    * int overflow, array bounds
    * special cases (n=1?)
    * do smth instead of nothing and stay organized
    * WRITE STUFF DOWN
*/

Compilation message (stderr)

pipes.cpp: In function 'void setIn(std::__cxx11::string)':
pipes.cpp:128:31: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
 void setIn(string s) { freopen(s.c_str(),"r",stdin); }
                        ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
pipes.cpp: In function 'void setOut(std::__cxx11::string)':
pipes.cpp:129:32: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
 void setOut(string s) { freopen(s.c_str(),"w",stdout); }
                         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

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