Submission #238937

#	Time	Username	Problem	Language	Result	Execution time	Memory
238937		rqi	Mergers (JOI19_mergers)	C++14	100 / 100	1320 ms	204488 KiB

mergers

#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: Calculates least common ancestor in tree 
     * with root $R$ using binary jumping. 
 * Time: O(N\log N) build, O(\log N) query
 * Memory: O(N\log N)
 * Source: USACO Camp
 * Verification: Debug the Bugs
 */

template<int SZ> struct LCA {
    static const int BITS = 32-__builtin_clz(SZ);
    int N, R = 1, par[BITS][SZ], depth[SZ], S[SZ], minb[SZ], blca[SZ]; vi adj[SZ], adj2[SZ], children[SZ]; bool forb[SZ]; 
    /// INITIALIZE
    void ae(int u, int v) { adj[u].pb(v), adj[v].pb(u); }
    void dfs(int u, int prv){
        depth[u] = depth[par[0][u] = prv]+1;
        children[prv].pb(u);
        trav(v,adj[u]) if (v != prv) dfs(v,u); }
    void init(int _N) {
        N = _N; dfs(R,0);
        FOR(k,1,BITS) FOR(i,1,N+1) 
            par[k][i] = par[k-1][par[k-1][i]];
    }
    /// QUERY
    int getPar(int a, int b) {
        R0F(k,BITS) if (b&(1<<k)) a = par[k][a];
        return a; }
    int lca(int u, int v){
        if (depth[u] < depth[v]) swap(u,v);
        u = getPar(u,depth[u]-depth[v]);
        R0F(k,BITS) if (par[k][u] != par[k][v]) 
            u = par[k][u], v = par[k][v];
        return u == v ? u : par[0][u];
    }
    int dist(int u, int v) { // # edges on path
        return depth[u]+depth[v]-2*depth[lca(u,v)]; }

    //NEW OPERATIONS
    int findMin(int node = 1){
        int val = depth[blca[S[node]]];
        for(auto u: children[node]){
            ckmin(val, findMin(u));
        }
        
        assert(val <= depth[node]);
        if(val == depth[node]){
            forb[node] = 1;
        }

        minb[node] = val;
        return val;
    }

    void genbPars(int node = 1, int t = 1){
        for(auto u: children[node]){
            if(forb[u] == 1){
                adj2[u].pb(t);
                adj2[t].pb(u);
                genbPars(u, u);
            }
            else{
                genbPars(u, t);
            }
        }
    }

    int getLeaves(){
        int leaves = 0;
        for(int i = 1; i <= N; i++){
            if(forb[i] == 0) continue;
            if(sz(adj2[i]) == 1){
                leaves++;
            }
        }
        return leaves;
    }
};

LCA<500005> tr;
int blca[500005];

int main() {
    setIO();
    int N, K;
    cin >> N >> K;
    for(int i = 1; i <= N-1; i++){
        int A, B;
        cin >> A >> B;
        tr.ae(A, B);
    }

    tr.init(N);

    for(int i = 1; i <= N; i++){
        cin >> tr.S[i];
        if(tr.blca[tr.S[i]] == 0){
            tr.blca[tr.S[i]] = i;
        }
        else{
            tr.blca[tr.S[i]] = tr.lca(i, tr.blca[tr.S[i]]);
        }
    }

    tr.findMin(); //find min-depth blca of children and self, mark forbidden vertices
    tr.genbPars(); //don't go to forbidden vertices, keep track of the forbidden vertex for each vertex, generate parents
    int num = tr.getLeaves(); //for each forbidden vertex, look at adj list and count leaves
    int ans = (num+1)/2;
    ps(ans);
    // 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)

mergers.cpp: In function 'void setIn(std::__cxx11::string)':
mergers.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); }
                        ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
mergers.cpp: In function 'void setOut(std::__cxx11::string)':
mergers.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: 24 / 24
• Subtask 3: 14 / 14
• Subtask 4: 22 / 22
• Subtask 5: 30 / 30