Submission #1069891

---

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 myPower(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;
int n, m;

vector<vector<int> > es, esrev;

int read() {
  if (scanf("%d%d", &n, &m) < 2) {
    return 0;
  }
  es = esrev = vector<vector<int> >(n);
  for (int i = 0; i < m; ++i) {
    int s, t;
    scanf("%d%d", &s, &t);
    --s, --t;
    es[s].pb(t);
    esrev[t].pb(s);
  }
  return 1;
}

int rem[maxn];

long long cnt[3];

bool fail;

int cnte;

void dfs(int v) {
  cnt[rem[v]] += 1;
  cnte += sz(es[v]);
  for (int u : es[v]) {
    int nrem = (rem[v] + 1) % 3;
    if (rem[u] != -1) {
      if (rem[u] != nrem) {
        fail = 1;
      }
      continue;
    }
    rem[u] = nrem;
    dfs(u);
  }
  for (int u : esrev[v]) {
    int nrem = (rem[v] + 2) % 3;
    if (rem[u] != -1) {
      if (rem[u] != nrem) {
        fail = 1;
      }
      continue;
    }
    rem[u] = nrem;
    dfs(u);
  }
}

void solve() {
  for (int i = 0; i < n; ++i) {
    rem[i] = -1;
  }

  long long res = 0;
  for (int i = 0; i < n; ++i) {
    if (rem[i] != -1) {
      continue;
    }
    memset(cnt, 0, sizeof(cnt));
    fail = 0;
    rem[i] = 0;
    cnte = 0;
    dfs(i);
    if (fail) {
      long long sum = cnt[0] + cnt[1] + cnt[2];
      res += sum * sum;
    } else {
      if (cnt[0] && cnt[1] && cnt[2]) {
        res += cnt[0] * cnt[1] + cnt[1] * cnt[2] + cnt[2] * cnt[0];
      } else {
        res += cnte;
      }
    }
  }
  printf("%lld\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:72:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d", &s, &t);
                          ^

Judge Result