单哈希模数过不去捏，求求能过的哈希模数。

#include <algorithm>
#include <iostream>
#include <cstring>
#include <cstdio>
#include <map>
#define int long long

using namespace std;

using PII = pair<int, int>;
const int N = 200010;
const int P = 23, mod = 19260817;

int n, m, a[N], b[N], ans;
int h1[N], h2[N], p[N], Base;
map<int, bool> Map;
PII tmp[N];

struct node {
	int l, r;
	int hash, size;
}tr[N << 2];
#define ls u << 1
#define rs u << 1 | 1

int Mod(int x) {
	return (x % mod + mod) % mod;
}
void pushup(int u) {
	tr[u].size = tr[ls].size + tr[rs].size;
	tr[u].hash = Mod(tr[rs].hash + Mod(tr[ls].hash * p[tr[rs].size]));
}
void build(int u, int l, int r) {
	tr[u] = {l, r, 0, 0};
	if (l == r) return;
	int mid = l + r >> 1;
	build(ls, l, mid), build(rs, mid + 1, r);
}
void insert(int u, int x, int v) {
	if (tr[u].l == tr[u].r) {
		tr[u].hash = v; tr[u].size = 1;
		return;
	}
	int mid = tr[u].l + tr[u].r >> 1;
	if (x <= mid) insert(ls, x, v);
	else insert(rs, x, v);
	pushup(u);
}
void remove(int u, int x) {
	if (tr[u].l == tr[u].r) {
		tr[u].hash = tr[u].size = 0;
		return;
	}
	int mid = tr[u].l + tr[u].r >> 1;
	if (x <= mid) remove(ls, x);
	else remove(rs, x);
	pushup(u);
}
int get_hash(int l, int r) {
	return ((h2[r] - h2[l - 1] * p[r - l + 1] % mod) % mod + mod) % mod;
}
signed main() {
	scanf("%lld%lld", &n, &m);
	for (int i = 1; i <= n; i ++ )
		scanf("%lld", &a[i]);
	for (int i = 1; i <= m; i ++ )
		scanf("%lld", &b[i]);
	p[0] = 1;
	for (int i = 1; i <= n; i ++ )
		h1[i] = (h1[i - 1] * P % mod + a[i]) % mod;
	for (int i = 1; i <= m; i ++ )
		h2[i] = (h2[i - 1] * P % mod + b[i]) % mod;
	for (int i = 1; i <= m; i ++ )
		p[i] = p[i - 1] * P % mod;
	for (int i = 0; i < n; i ++ )
		Base = (Base + p[i]) % mod;
	for (int i = 0; i <= m - n; i ++ ) // O(m \log n) has been used. Here.
		Map[(h1[n] + Base * i % mod) % mod] = true;
	
	for (int i = 1; i <= m; i ++ )
		tmp[i] = {b[i], i};
	sort(tmp + 1, tmp + m + 1);
	build(1, 1, m);
	for (int i = 1; i <= n; i ++ )
		insert(1, tmp[i].second, tmp[i].first);
	for (int i = n + 1; i <= m; i ++ ) {	
		int hash = tr[1].hash;
		if (Map[hash]) ans ++ ;
		remove(1, tmp[i - n].second);
		insert(1, tmp[i].second, tmp[i].first);
	}
	if (Map[tr[1].hash]) ans ++ ;
	cout << ans << endl;
	return 0;
}

$p = 13, mod = 10 ^ 9 + 7$

$p = 1331, mod = 998244353$

$p = 13, mod = 999988883$

都不过。