Submission #274892

#	Time	Username	Problem	Language	Result	Execution time	Memory
274892		rqi	medians (balkan11_medians)	C++14	100 / 100	30 ms	3064 KiB

medians

#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<bool> vb; 
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 sor(x) sort(all(x)) 
#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; } 
constexpr int pct(int x) { return __builtin_popcount(x); } 
constexpr int bits(int x) { return 31-__builtin_clz(x); } // floor(log2(x)) 
ll cdiv(ll a, ll b) { return a/b+((a^b)>0&&a%b); } // divide a by b rounded up
ll fdiv(ll a, ll b) { return a/b-((a^b)<0&&a%b); } // divide a by b rounded down
ll half(ll x) { return fdiv(x,2); }

template<class T, class U> T fstTrue(T lo, T hi, U f) { 
    // note: if (lo+hi)/2 is used instead of half(lo+hi) then this will loop infinitely when lo=hi
    hi ++; assert(lo <= hi); // assuming f is increasing
    while (lo < hi) { // find first index such that f is true 
        T mid = half(lo+hi);
        f(mid) ? hi = mid : lo = mid+1; 
    } 
    return lo;
}
template<class T, class U> T lstTrue(T lo, T hi, U f) {
    lo --; assert(lo <= hi); // assuming f is decreasing
    while (lo < hi) { // find first index such that f is true 
        T mid = half(lo+hi+1);
        f(mid) ? lo = mid : hi = mid-1;
    } 
    return lo;
}
template<class T> void remDup(vector<T>& v) { 
    sort(all(v)); v.erase(unique(all(v)),end(v)); }

// 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(const char* s) { return (str)s; }
str ts(str s) { return s; }
str ts(bool b) { 
    #ifdef LOCAL
        return b ? "true" : "false"; 
    #else 
        return ts((int)b);
    #endif
}
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()
    #ifdef LOCAL
        bool fst = 1; str res = "{";
        for (const auto& x: v) {
            if (!fst) res += ", ";
            fst = 0; res += ts(x);
        }
        res += "}"; return res;
    #else
        bool fst = 1; str res = "";
        for (const auto& x: v) {
            if (!fst) res += " ";
            fst = 0; res += ts(x);
        }
        return res;

    #endif
}
template<class A, class B> str ts(pair<A,B> p) {
    #ifdef LOCAL
        return "("+ts(p.f)+", "+ts(p.s)+")"; 
    #else
        return ts(p.f)+" "+ts(p.s);
    #endif
}

// 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, chk -> fake assert
    #define dbg(...) cerr << "Line(" << __LINE__ << ") -> [" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
    #define chk(...) if (!(__VA_ARGS__)) cerr << "Line(" << __LINE__ << ") -> function(" \
         << __FUNCTION__  << ") -> CHK FAILED: (" << #__VA_ARGS__ << ")" << "\n", exit(0);
#else
    #define dbg(...) 0
    #define chk(...) 0
#endif

// FILE I/O
void setIn(str s) { freopen(s.c_str(),"r",stdin); }
void setOut(str s) { freopen(s.c_str(),"w",stdout); }
void unsyncIO() { cin.tie(0)->sync_with_stdio(0); }
void setIO(str 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: A set (not multiset!) with support for finding the $n$'th
 * element, and finding the index of an element. Change \texttt{null\_type} for map.
 * Time: O(\log N)
 * Source: KACTL
   * https://codeforces.com/blog/entry/11080
 * Verification: many
 */

#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template <class T> using Tree = tree<T, null_type, less<T>, 
    rb_tree_tag, tree_order_statistics_node_update>; 
#define ook order_of_key
#define fbo find_by_order

void treeExample() {
    Tree<int> t, t2; t.insert(8);
    auto it = t.insert(10).f; assert(it == t.lb(9));
    assert(t.ook(10) == 1 && t.ook(11) == 2 && *t.fbo(0) == 8);
    t.join(t2); // assuming T < T2 or T > T2, merge t2 into t
}

/**
int atMost(Tree<pi>& T, int r) { 
    return T.ook({r,MOD}); }
int getSum(Tree<pi>& T, int l, int r) { 
    return atMost(T,r)-atMost(T,l-1); }
*/

int N;
const int mx = 200005;
int B[mx];
int A[mx];
bool inB[mx];
bool used[mx];

vi get(){
    vi b;
    Tree<int> t;
    for(int i = 1; i <= 2*N-1; i++){
        t.ins(A[i]);
        if(i % 2 == 1){
            b.pb(*(t.fbo(i/2)));
        }
    }
    return b;
}

int main() {
    setIO();
    cin >> N;
    for(int i = 1; i <= N; i++){
        cin >> B[i];
    }
    for(int i = 1; i <= N; i++){
        inB[B[i]] = 1;
    }
    int lo = 1;
    int hi = 2*N-1;
    A[1] = B[1];
    used[A[1]] = 1;
    for(int i = 2; i <= N; i++){
        //dbg(i, A[2*i-4], A[2*i-3]);
        //dbg(used[4]);
        //dbg(lo, hi);
        if(B[i] > B[i-1]){
            while(inB[hi]){
                hi--;
            }
            A[2*i-2] = hi;
            hi--;
            if(used[B[i]]){
                while(inB[hi]){
                    hi--;
                }
                A[2*i-1] = hi;
                hi--;
            }
            else{
                A[2*i-1] = B[i];
            }
        }
        else if(B[i] == B[i-1]){
            while(inB[hi]){
                hi--;
            }
            A[2*i-2] = hi;
            hi--;
            while(inB[lo]){
                lo++;
            }
            A[2*i-1] = lo;
            lo++;
        }
        else{
            while(inB[lo]){
                //dbg(lo);
                lo++;
            }
            A[2*i-2] = lo;
            lo++;
            if(used[B[i]]){
                while(inB[lo]){
                    //dbg(lo);
                    lo++;
                }
                A[2*i-1] = lo;
                lo++;
            }
            else{
                A[2*i-1] = B[i];
            }
        }
        used[A[2*i-1]] = 1;
    }

    for(int i = 1; i <= 2*N-1; i++){
        used[i] = 0;
    }
    for(int i = 1; i <= 2*N-1; i++){
        used[A[i]] = 1;
    }
    for(int i = 1; i <= 2*N-1; i++){
        assert(used[i]);
    }
    for(int i = 1; i <= 2*N-1; i++){
        cout << A[i] << " ";
    }
    cout << "\n";

    // vi b = get();
    // for(int i = 1; i <= N; i++){
    //     assert(b[i-1] == B[i]);
    // }
    // 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)

medians.cpp: In function 'void setIn(str)':
medians.cpp:168:28: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
  168 | void setIn(str s) { freopen(s.c_str(),"r",stdin); }
      |                     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
medians.cpp: In function 'void setOut(str)':
medians.cpp:169:29: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
  169 | void setOut(str s) { freopen(s.c_str(),"w",stdout); }
      |                      ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 65 / 65
• Subtask 2: 35 / 35