Submission #7562739

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;

#define int long long
#define rep(i,l,r) for(int i=(int)(l);i<(int)(r);i++)
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)x.size())
template<class T>bool chmax(T &a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T>bool chmin(T &a,T b){if(a>b){a=b;return 1;}return 0;}

typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;

const int inf = 1LL<<60;
const int mod = 1e9 + 7;
const double eps = 1e-9;

/*{
  }*/

signed main(){
  int n, m;
  cin >> n >> m;

  vi a(n);
  rep(i, 0, n) cin >> a[i];

  vector<multiset<int>> cnt(m);
  rep(i, 0, n){
    cnt[a[i]%m].insert(a[i]);
  }

  int ans = sz(cnt[0])/2;
  rep(i, 1, m/2+1){
    cout << i-1 << " " << ans << endl;
    if(m%2 == 0 and i == m/2){
      ans += sz(cnt[m/2])/2;
      continue;
    }

    int t = sz(cnt[i]) - sz(cnt[m-i]);
    if(t < 0){
      t = -t;
      swap(cnt[i], cnt[m-i]);
    }

    ans += sz(cnt[m-i]);

    int k = 2, prev = -1;
    for(int j : cnt[i]){
      if(k > t) break;
      if(prev == j){
        ans += 1;
        k += 2;
        prev = -1;
      }else{
        prev = j;
      }
    }
  }

  cout << ans << endl;

  return 0;
}

Submission Info

Judge Result