Submission #992265

---

Source Code Expand

#ifdef DEBUG
#define _GLIBCXX_DEBUG
#endif

#include <bits/stdc++.h>

using namespace std;

mt19937 mrand(random_device{} ()); 

int rnd(int x) {
  return mrand() % x;
}

typedef long double ld;
typedef long long ll;

#ifdef DEBUG
#define eprintf(...) fprintf(stderr, __VA_ARGS__), fflush(stderr)
#else
#define eprintf(...) ;
#endif

#define pb push_back
#define mp make_pair
#define sz(x) ((int) (x).size())
#define TASK "text"

const int inf = (int) 1.01e9;
const ld eps = 1e-9;
const ld pi = acos((ld) -1.0);

void precalc() {
}

const int maxn = (int) 1e5 + 10;
int a[maxn];
int n, m;

int read() {
  if (scanf("%d%d", &n, &m) < 2) {
    return 0;
  }
  for (int i = 0; i < n; ++i) {
    scanf("%d", a + i);
  }
  return 1;
}

pair<int, int> ps[maxn];

int b[maxn][2];

void solve() {
  sort(a, a + n);
  for (int i = 0; i < m; ++i) {
    b[i][0] = b[i][1] = 0;
  }
  for (int i = 0; i < n;) {
    int i0 = i;
    while (i < n && a[i] == a[i0]) {
      ++i;
    }
    int r = a[i0] % m;
    b[r][0] += (i - i0) / 2;
    b[r][1] += (i - i0) % 2;
    //eprintf("%d  %d\n", r, i - i0);
  }

  int res = 0;

  for (int i = 0; i <= m - i; ++i) {
    if (!i || i == m - i) {
      res += b[i][0] + b[i][1] / 2;
    } else {
      //eprintf("%d %d\n", i, m - i);
      while (1) {
        if ((!b[i][0] && !b[i][1]) || (!b[m - i][0] && !b[m - i][1])) {
          res += b[i][0] + b[m - i][0];
          break;
        }
        //eprintf("%d %d   %d %d\n", b[i][0], b[i][1], b[m - i][0], b[m - i][1]);
        for (int it = 0; it < 2; ++it) {
          int x = !it ? i : (m - i);
          if (b[x][1]) {
            --b[x][1];
            continue;
          }
          if (b[x][0]) {
            ++b[x][1];
            --b[x][0];
            continue;
          }
          assert(0);
        }
        ++res;
      }
    }
  }
  printf("%d\n", res);
}

int main() {
  precalc();
#ifdef LOCAL
  freopen(TASK ".out", "w", stdout);
  assert(freopen(TASK ".in", "r", stdin));
#endif

  while (1) {
    if (!read()) {
      break;
    }
    solve();
#ifdef DEBUG
    eprintf("Time %.2f\n", (double) clock() / CLOCKS_PER_SEC);
#endif
  }
  return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int read()’:
./Main.cpp:45:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", a + i);
                       ^

Judge Result