Contest Duration: ~ (local time) (180 minutes)

Submission #5418795

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```#include <iostream>
#include <iomanip>
#include <string>
#include <cmath>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <list>
#include <stack>
#include <queue>
#include <bitset>
#include <numeric>

/* (=＾o＾=) */
#define int ll

/* macro */
#define FOR(i, b, e) for(ll i = (ll)(b); i < (ll)(e); ++i)
#define RFOR(i, b, e) for(ll i = (ll)(e-1); i >= (ll)(b); --i)
#define REP(i, n) FOR(i, 0, n)
#define RREP(i, n) RFOR(i, 0, n)
#define REPC(x,c) for(const auto& x:(c))
#define REPI2(it,b,e) for(auto it = (b); it != (e); ++it)
#define REPI(it,c) REPI2(it, (c).begin(), (c).end())
#define RREPI(it,c) REPI2(it, (c).rbegin(), (c).rend())
#define REPI_ERACE2(it, b, e) for(auto it = (b); it != (e);)
#define REPI_ERACE(it, c) REPI_ERACE2(it, (c).begin(), (c).end())
#define ALL(x) (x).begin(),(x).end()
#define cauto const auto&
/* macro func */
#define SORT(x) do{sort(ALL(x));}while(false)
#define RSORT(x) do{sort((x).rbegin(),(x).rend());}while(false)
#define UNIQUE(v) do{v.erase( unique(v.begin(), v.end()), v.end() );}while(false)
#define MAX(x,y) do{x = std::max(x,y);}while(false)
#define MIN(x,y) do{x = std::min(x,y);}while(false)
#define BR do{cout<<"\n";}while(false)
#define dump(...) do{ auto __DUMP_NAME_LIST__ = split(#__VA_ARGS__,','); print(__DUMP_NAME_LIST__, __VA_ARGS__);BR;}while(false)

/* type define */
using ll = long long;
using PAIR = std::pair<ll, ll>;
using VS = std::vector<std::string>;
using VL = std::vector<long long>;
using VVL = std::vector<VL>;
using VVVL = std::vector<VVL>;
using VD = std::vector<double>;

/* using std */
using std::cout;
constexpr char endl = '\n';
using std::cin;
using std::sort;
using std::pair;
using std::string;
using std::stack;
using std::queue;
using std::vector;
using std::list;
using std::map;
using std::unordered_map;
using std::multimap;
using std::unordered_multimap;
using std::set;
using std::unordered_set;
using std::unordered_multiset;
using std::multiset;
using std::bitset;
using std::priority_queue;

/* constant value */
constexpr ll MOD = 1000000007;
//constexpr ll MOD = 998244353;

/* Initial processing  */
struct Preprocessing { Preprocessing() { std::cin.tie(0); std::ios::sync_with_stdio(0); }; }_Preprocessing;

/* define hash */
namespace std { template <>	class hash<std::pair<ll, ll>> { public:	size_t operator()(const std::pair<ll, ll>& x) const { return hash<ll>()(1000000000 * x.first + x.second); } }; }

/* input output */
template<class T> std::istream& operator >> (std::istream& is, vector<T>& vec) { for (T& x : vec) is >> x; return is; }
template<class S, class T>std::ostream& operator<<(std::ostream & os, const std::pair<S, T> & p) { os << "(" << p.first << ", " << p.second << ")"; return os; }

/* for dump function */
inline std::list<std::string> split(std::string str, char del) { std::list<std::string> sList; string s = ""; for (const auto& c : str) { if (c == del) { sList.emplace_back(s); s = ""; } else { if (c != ' ' || del == ' ') { s += c; } } }sList.emplace_back(s);	return sList; }
template<class T>struct has_begin { private:	template <class U>	static auto check(U x) -> decltype(x.begin(), std::true_type{});	static std::false_type check(...); public:	static bool const value = decltype(check(std::declval<T>()))::value; };
inline void print(std::list<std::string> & str); template<class Primitive, class... Tail, std::enable_if_t<!has_begin<Primitive>::value, std::nullptr_t> = nullptr>inline void print(std::list<std::string> & str, const Primitive & x, const Tail & ... tail); template<class Container, class... Tail>inline auto print(std::list<std::string> & str, const Container & c, const Tail & ... tail) -> decltype(c.begin()); template<class... Tail>inline void print(std::list<std::string> & str, const std::string & s, const Tail & ... tail);
template<class Container>inline auto printSingle(const Container & c) ->decltype(c.begin()) { for (const auto& x : c) { std::cout << x << " "; }std::cout << "\n"; return c.begin(); }
template<class Primitive, std::enable_if_t<!has_begin<Primitive>::value, std::nullptr_t> = nullptr>inline void printSingle(const Primitive & x) { std::cout << x << " "; }
inline void print(std::list<std::string> & str) {}
template<class Primitive, class... Tail, std::enable_if_t<!has_begin<Primitive>::value, std::nullptr_t> = nullptr>inline void print(std::list<std::string> & str, const Primitive & x, const Tail & ... tail) { std::cout << *str.begin() << ":" << x << " "; if (sizeof...(tail) > 0) { std::cout << "\n"; str.pop_front(); print(str, tail...); } }
template<class Container, class... Tail>inline auto print(std::list<std::string> & str, const Container & c, const Tail & ... tail) ->decltype(c.begin()) { std::cout << "-- " << *str.begin() << " --\n"; for (const auto& x : c) { printSingle(x); BR; }std::cout << "\n"; str.pop_front();	print(str, tail...); return c.begin(); }
template<class... Tail>inline void print(std::list<std::string> & str, const std::string & s, const Tail & ... tail) { std::cout << *str.begin() << ":" << s << "\n"; str.pop_front();	print(str, tail...); }

//=============================================================================================

signed main() {
ll n, m;
cin >> n >> m;
VL v(n);
cin >> v;

unordered_map<ll, ll> mp;
REPC(x, v) {
mp[x]++;
}

vector<PAIR> t(m);
REPC(p, mp) {
ll it = p.first % m;
ll k = p.second;
t[it].first += k / 2;
t[it].second += k % 2;
}
ll ans = 0;
ans += t[0].first + t[0].second / 2;
if (m % 2 == 0) {
ans += t[m / 2].first + t[m / 2].second / 2;
}
// dump(t, ans);
FOR(i, 1, (m + 1) / 2) {
auto& l = t[i];
auto& r = t[m - i];
ll mn = std::min(l.second, r.second);
ans += mn;
if (l.second > r.second) {
ll d = (l.second - mn) / 2;
ll mn2 = std::min(d, r.first);
ans += mn2 * 2;
r.first -= mn2;
} else {
ll d = (r.second - mn) / 2;
ll mn2 = std::min(d, l.first);
ans += mn2 * 2;
l.first -= mn2;
}

ans += t[i].first;
ans += t[m - i].first;
}
cout << ans << endl;
// dump(ans);
}

```

#### Submission Info

Submission Time 2019-05-16 21:39:45+0900 D - Pair Cards cutmdo C++14 (GCC 5.4.1) 700 6235 Byte AC 23 ms 6692 KB

#### Judge Result

Set Name Score / Max Score Test Cases
sample 0 / 0 sample-01.txt, sample-02.txt
all 700 / 700 sample-01.txt, sample-02.txt, 01-01.txt, 01-02.txt, 01-03.txt, 01-04.txt, 01-05.txt, 01-06.txt, 01-07.txt, 01-08.txt, 01-09.txt, 01-10.txt, 01-11.txt, 01-12.txt, 01-13.txt, 01-14.txt, 01-15.txt, 01-16.txt, 01-17.txt, 01-18.txt, 01-19.txt, 01-20.txt, 01-21.txt, 01-22.txt, 01-23.txt, 01-24.txt, 01-25.txt, 01-26.txt, 01-27.txt, 01-28.txt, 01-29.txt, 01-30.txt, sample-01.txt, sample-02.txt
Case Name Status Exec Time Memory
01-01.txt 1 ms 256 KB
01-02.txt 21 ms 4492 KB
01-03.txt 21 ms 4492 KB
01-04.txt 20 ms 4492 KB
01-05.txt 21 ms 4492 KB
01-06.txt 21 ms 4492 KB
01-07.txt 21 ms 4492 KB
01-08.txt 21 ms 4492 KB
01-09.txt 21 ms 4492 KB
01-10.txt 21 ms 4644 KB
01-11.txt 22 ms 5540 KB
01-12.txt 10 ms 1024 KB
01-13.txt 10 ms 1792 KB
01-14.txt 22 ms 5156 KB
01-15.txt 22 ms 5156 KB
01-16.txt 22 ms 5156 KB
01-17.txt 22 ms 5156 KB
01-18.txt 22 ms 5156 KB
01-19.txt 22 ms 5412 KB
01-20.txt 23 ms 6692 KB
01-21.txt 11 ms 1280 KB
01-22.txt 12 ms 1280 KB
01-23.txt 11 ms 1280 KB
01-24.txt 11 ms 1280 KB
01-25.txt 12 ms 1664 KB
01-26.txt 12 ms 2816 KB
01-27.txt 12 ms 4236 KB
01-28.txt 3 ms 1920 KB
01-29.txt 2 ms 896 KB
01-30.txt 2 ms 1792 KB
sample-01.txt 1 ms 256 KB
sample-02.txt 1 ms 256 KB