Ctrl-F

#include <bits/stdc++.h>
using namespace std;
#define all(x) (x).begin(), (x).end()
#define mp make_pair
#define fi first
#define se second
#define pb push_back
#define IOS ios_base::sync_with_stdio(0), cin.tie(0)
const int INF = 1001001001;
const int MAXN = 100'000;
const char br = '\n';
using ll = long long;
using vi = vector<int>;
using pii = pair<int, int>;

// === Debug macro starts here ===

int recur_depth = 0;
#ifdef DEBUG
#define dbg(x)                                                                 \
	{                                                                      \
		++recur_depth;                                                 \
		auto x_ = x;                                                   \
		--recur_depth;                                                 \
		cerr << string(recur_depth, '\t') << "\e[91m" << __func__      \
		     << ":" << __LINE__ << "\t" << #x << " = " << x_           \
		     << "\e[39m" << endl;                                      \
	}
#else
#define dbg(x)
#endif
template <typename Ostream, typename Cont>
typename enable_if<is_same<Ostream, ostream>::value, Ostream &>::type
operator<<(Ostream &os, const Cont &v) {
	os << "[";
	for (auto &x : v) {
		os << x << ", ";
	}
	return os << "]";
}

// === Debug macro ends here ===

// print pair, vector
template <typename Ostream, typename... Ts>
Ostream &operator<<(Ostream &os, const pair<Ts...> &p) {
	return os << "{" << p.first << ", " << p.second << "}";
}
template <typename T> ostream &operator<<(ostream &s, vector<T> t) {
	for (const T &v : t) {
		cout << v << " ";
	}
	return s;
}

int nxt() {
	int x;
	cin >> x;
	return x;
}

vector<int> z_function(string const &s) {
	int n = s.size();
	vector<int> z(n);
	// z[0] = n;
	int l = 0, r = 0;
	for (int i = 1; i < n; i++) {
		if (i < r)
			z[i] = min(r - i, z[i - l]);
		while (i + z[i] < n && s[z[i]] == s[i + z[i]])
			z[i]++;
		if (i + z[i] > r) {
			l = i;
			r = i + z[i];
		}
	}
	return z;
}

int main() {
	IOS;

	string a;
	string b;
	cin >> a >> b;

	int alen = a.size();
	auto z = z_function(a + "#" + b);

	int count = 0;
	vi places;
	for (size_t i = 0; i < z.size(); i++) {
		if (z[i] == alen) {
			count++;
			places.pb(i - alen);
		}
	}

	cout << count << br;
	cout << places << br;

	return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED

Test 23

Verdict: ACCEPTED

Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED

Test 26

Verdict: ACCEPTED

Test 27

Verdict: ACCEPTED

Test 28

Verdict: ACCEPTED

Test 29

Verdict: ACCEPTED

Test 30

Verdict: ACCEPTED

Test 31

Verdict: ACCEPTED

Test 32

Verdict: ACCEPTED

Test 33

Verdict: ACCEPTED

Test 34

Verdict: ACCEPTED

Test 35

Verdict: ACCEPTED

Test 36

Verdict: ACCEPTED

Test 37

Verdict: ACCEPTED

Test 38

Verdict: ACCEPTED

Test 39

Verdict: ACCEPTED

Test 40

Verdict: ACCEPTED

Test 41

Verdict: ACCEPTED

Test 42

Verdict: ACCEPTED

Test 43

Verdict: ACCEPTED

Test 44

Verdict: ACCEPTED

Test 45

Verdict: ACCEPTED

Test 46

Verdict: ACCEPTED

Test 47

Verdict: ACCEPTED

Test 48

Verdict: ACCEPTED

Test 49

Verdict: ACCEPTED

Test 50

Verdict: ACCEPTED

Test 51

Verdict: ACCEPTED

Test 52

Verdict: ACCEPTED

Test 53

Verdict: ACCEPTED

Test 54

Verdict: ACCEPTED

Test 55

Verdict: ACCEPTED

Test 56

Verdict: ACCEPTED

Test 57

Verdict: ACCEPTED

Test 58

Verdict: ACCEPTED

Test 59

Verdict: ACCEPTED

Test 60

Verdict: ACCEPTED

Test 61

Verdict: ACCEPTED

Test 62

Verdict: ACCEPTED

Test 63

Verdict: ACCEPTED

Test 64

Verdict: ACCEPTED

Test 65

Verdict: ACCEPTED

Test 66

Verdict: ACCEPTED

Test 67

Verdict: ACCEPTED

Test 68

Verdict: ACCEPTED

Test 69

Verdict: ACCEPTED

Test 70

Verdict: ACCEPTED

Test 71

Verdict: ACCEPTED

Test 72

Verdict: ACCEPTED

Test 73

Verdict: ACCEPTED

Test 74

Verdict: ACCEPTED

Test 75

Verdict: ACCEPTED

Test 76

Verdict: ACCEPTED

Test 77

Verdict: ACCEPTED

Test 78

Verdict: ACCEPTED

Test 79

Verdict: ACCEPTED

Test 80

Verdict: ACCEPTED

Test 81

Verdict: ACCEPTED

Test 82

Verdict: ACCEPTED

Test 83

Verdict: ACCEPTED

Test 84

Verdict: ACCEPTED

Test 85

Verdict: ACCEPTED

Test 86

Verdict: ACCEPTED

Test 87

Verdict: ACCEPTED

Test 88

Verdict: ACCEPTED

Test 89

Verdict: ACCEPTED

Test 90

Verdict: ACCEPTED

Test 91

Verdict: ACCEPTED

Test 92

Verdict: ACCEPTED

Test 93

Verdict: ACCEPTED