Submission #1303229

---

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);

const int mod = (int) 1e9 + 7;

void add(int &x, int y) {
  if ((x += y) >= mod) {
    x -= mod;
  }
}

int mult(int x, int y) {
  return (long long) x * y % mod;
}

int power(int x, int pw) {
  int res = 1;
  for (; pw; pw >>= 1) {
    if (pw & 1) {
      res = mult(res, x);
    }
    x = mult(x, x);
  }
  return res;
}

void precalc() {
}


const int maxn = (int) 1e5 + 10;
pair<int, int> tosort[maxn];

int n;

int read() {
  if (scanf("%d", &n) < 1) {
    return 0;
  }
  for (int i = 0; i < n; ++i) {
    int x, y;
    scanf("%d%d", &x, &y);
    tosort[i] = mp(x, y);
  }
  return 1;
}

void solve() {
  if (tosort[0].first || tosort[1].second) {
    printf("-1\n");
    return;
  }
  map<pair<int, int>, int> cnt;
  for (int i = 0; i < n; ++i) {
    int x = tosort[i].first;
    int y = tosort[i].second;
    if (i != 0 && !x) {
      printf("-1\n");
      return;
    }
    if (i != 1 && !y) {
      printf("-1\n");
      return;
    }
    cnt[{x, y}] += 1;
    tosort[i] = {x + y, y};
  }
  sort(tosort, tosort + n);

  int res = 2 * n - 2;
  for (int i = 0; i < n;) {
    int i0 = i;
    while (i < n && tosort[i].first == tosort[i0].first) {
      int x = tosort[i].first, y = tosort[i].second;
      x -= y;

      for (int iter = 0; iter < 2; ++iter) {
        auto &cur = (!iter ? x : y);
        if (!cur) {
          continue;
        }
        auto &cury = (iter ? x : y);
        --cur;
        bool ok = 0;
        for (int dx = -1; dx <= 1; ++dx) {
          cury += dx;
          if (cnt.count({x, y})) {
            ok = 1;
          }
          cury -= dx;
        }
        ++cur;
        if (!ok) {
          printf("-1\n");
          return;
        }
      }
      ++i;
    }

    int last = 0, left = 0;
    for (int j = i0; j < i;) {
      int j0 = j;
      while (j < i && tosort[j].second == tosort[j0].second) {
        ++j;
      }
      int now = j - j0;

      int del = 0;
      if (last + 1 == tosort[j0].second) {
        del = min(now, left);
        res -= del;
      }
      if (cnt.count({tosort[j0].first - tosort[j0].second - 1, tosort[j0].second - 1})) {
        res -= now - del;
        now = del;
      }
      left = now;
      last = tosort[j0].second;
    }
  }
  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:71:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d", &x, &y);
                          ^

Judge Result