Language: C++

/*
    _____
  .'     '.
 /  0   0  \
|     ^     |
|  \     /  |
 \  '---'  /
  '._____.'
*/
#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>

using namespace std;
using namespace __gnu_pbds;

struct chash
{
	int operator()(int x) const
	{
		x ^= (x >> 20) ^ (x >> 12);
		return x ^ (x >> 7) ^ (x >> 4);
	}
};

template<typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T, typename U> using hashtable = gp_hash_table<T, U, chash>;
random_device(rd);
mt19937 rng(rd());

template<class T>
void readi(T &x)
{
	T input = 0;
	bool negative = false;
	char c = ' ';
	while (c < '-')
	{
		c = getchar();
	}
	if (c == '-')
	{
		negative = true;
		c = getchar();
	}
	while (c >= '0')
	{
		input = input * 10 + (c - '0');
		c = getchar();
	}
	if (negative)
	{
		input = -input;
	}
	x = input;
}
template<class T>
void printi(T output)
{
	if (output == 0)
	{
		putchar('0');
		return;
	}
	if (output < 0)
	{
		putchar('-');
		output = -output;
	}
	int aout[20];
	int ilen = 0;
	while(output)
	{
		aout[ilen] = ((output % 10));
		output /= 10;
		ilen++;
	}
	for (int i = ilen - 1; i >= 0; i--)
	{
		putchar(aout[i] + '0');
	}
	return;
}
template<class T>
void ckmin(T &a, T b)
{
	a = min(a, b);
}
template<class T>
void ckmax(T &a, T b)
{
	a = max(a, b);
}
template<class T, class U>
T nmod(T &x, U mod)
{
	if (x >= mod) x -= mod;
}
template<class T>
T randomize(T mod)
{
	return (uniform_int_distribution<T>(0, mod - 1))(rng);
}

#define y0 ___y0
#define y1 ___y1
#define MP make_pair
#define MT make_tuple
#define PB push_back
#define PF push_front
#define LB lower_bound
#define UB upper_bound
#define fi first
#define se second
#define debug(x) cerr << #x << " = " << x << endl;

const long double PI = 4.0 * atan(1.0);
const long double EPS = 1e-10;

#define MAGIC 347
#define SINF 10007
#define CO 1000007
#define INF 1000000007
#define BIG 1000000931
#define LARGE 1696969696967ll
#define GIANT 2564008813937411ll
#define LLINF 2696969696969696969ll
#define MAXN 500013

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<ld, ld> pdd;

int N;
int arr[MAXN];
pll S;
long long ans;
unordered_map<ll, int> need;

ll expo(ll a, ll e, ll mod)
{
	if (e == 0)
	{
		return 1;
	}
	ll was = expo(a, e / 2, mod);
	if (e % 2)
	{
		return was * was % mod * a % mod;
	}
	return was * was % mod;
}
ll modinv(ll a, ll e)
{
	return expo(a, e - 2, e);
}
pll INV = {modinv(CO, INF), modinv(CO, BIG)};
void solve(int L, int R)
{
	if (L == R)
	{
		return;
	}
	freq.clear(); need.clear();
	int mid = (L + R) >> 1;
	//start from L...mid, end at mid + 1....R
	pair<pll, pll> trans = MP(MP(1, 0), MP(1, 0));
	for (int i = mid + 1; i <= R; i++)
	{
		if (arr[i] == 0)
		{
			trans.fi.fi *= INV.fi; trans.fi.fi %= INF;
			trans.fi.se *= INV.fi; trans.fi.se %= INF;
			trans.se.fi *= INV.se; trans.se.fi %= BIG;
			trans.se.se *= INV.se; trans.se.se %= BIG;
		}
		if (arr[i] == 1)
		{
			trans.fi.fi *= CO; trans.fi.fi %= INF;
			trans.fi.se *= CO; trans.fi.se %= INF;
			trans.se.fi *= CO; trans.se.fi %= BIG;
			trans.se.se *= CO; trans.se.se %= BIG;
		}
		if (arr[i] == 2)
		{
			trans.fi.se++; nmod(trans.fi.se, INF);
			trans.se.se++; nmod(trans.se.se, BIG);
		}
		if (arr[i] == 3)
		{
			trans.fi.se--; trans.fi.se += INF; nmod(trans.fi.se, INF);
			trans.se.se--; trans.se.se += BIG; nmod(trans.se.se, BIG);
		}
		pll dif = {(S.fi - trans.fi.se) * modinv(trans.fi.fi, INF), (S.se - trans.se.se) * modinv(trans.se.fi, BIG)};
		dif.fi %= INF; dif.fi += INF; nmod(dif.fi, INF);
		dif.se %= BIG; dif.se += BIG; nmod(dif.se, BIG);
		need[dif.fi * BIG + dif.se]++;
	}
	trans = MP(MP(1, 0), MP(1, 0));
	for (int i = mid; i >= L; i--)
	{
		if (arr[i] == 0)
		{
			trans.fi.fi *= INV.fi; trans.fi.fi %= INF;
			trans.se.fi *= INV.se; trans.se.fi %= BIG;
		}
		if (arr[i] == 1)
		{
			trans.fi.fi *= CO; trans.fi.fi %= INF;
			trans.se.fi *= CO; trans.se.fi %= BIG;
		}
		if (arr[i] == 2)
		{
			trans.fi.se += trans.fi.fi; nmod(trans.fi.se, INF);
			trans.se.se += trans.se.fi; nmod(trans.se.se, BIG);
		}
		if (arr[i] == 3)
		{
			trans.fi.se -= trans.fi.fi; trans.fi.se += INF; nmod(trans.fi.se, INF);
			trans.se.se -= trans.se.fi;	trans.se.se += BIG; nmod(trans.se.se, BIG);
		}
		ans += need[trans.fi.se * BIG + trans.se.se];
	}
	solve(L, mid);
	solve(mid + 1, R);
}

int32_t main()
{
	ios_base::sync_with_stdio(0);
	// cout << fixed << setprecision(10);
	// cerr << fixed << setprecision(10);
	// freopen ("file.in", "r", stdin);
	// freopen ("file.out", "w", stdout);
	cin >> N;
	string temps;
	cin >> temps;
	for (int i = 0; i < N; i++)
	{
		if (temps[i] == '<')
		{
			arr[i] = 0;
		}
		if (temps[i] == '>')
		{
			arr[i] = 1;
		}
		if (temps[i] == '+')
		{
			arr[i] = 2;
		}
		if (temps[i] == '-')
		{
			arr[i] = 3;
		}
	}
	reverse(arr, arr + N);
	for (int i = 0; i < N; i++)
	{
		if (arr[i] == 0)
		{
			S.fi *= INV.fi; S.fi %= INF;
			S.se *= INV.se; S.se %= BIG;
			// cerr << "times " << INV << endl;
		}
		if (arr[i] == 1)
		{
			S.fi *= CO; S.fi %= INF;
			S.se *= CO; S.se %= BIG;
			// cerr << "times " << CO << endl;
		}
		if (arr[i] == 2)
		{
			S.fi++; nmod(S.fi, INF);
			S.se++; nmod(S.se, BIG);
			// cerr << "add 1\n";
		}
		if (arr[i] == 3)
		{
			S.fi--; S.fi += INF; nmod(S.fi, INF);
			S.se--; S.se += BIG; nmod(S.se, BIG);
			// cerr << "add -1\n";
		}
	}
	for (int i = 0; i < N; i++)
	{
		if (arr[i] == 0)
		{
			if (S == MP(0ll, 0ll)) ans++;
		}
		if (arr[i] == 1)
		{
			if (S == MP(0ll, 0ll)) ans++;
		}
		if (arr[i] == 2)
		{
			if (S == MP(1ll, 1ll)) ans++;
		}
		if (arr[i] == 3)
		{
			if (S == MP((ll) INF - 1, (ll) BIG - 1)) ans++;
		}
	}
	solve(0, N - 1);
	cout << ans << '\n';
	//when u <, the # divides by co
	//when u >, the # mults by co
	//when u +, u add the #
	//when u -, u subtract the #
	// cerr << "time elapsed = " << (clock() / (CLOCKS_PER_SEC / 1000)) << " ms" << endl;
	return 0;
}


Compiler output:
a.cc: In function 'void solve(int, int)':
a.cc:166:9: error: 'freq' was not declared in this scope; did you mean 'free'?
  166 |         freq.clear(); need.clear();
      |         ^~~~
      |         free
a.cc: In instantiation of 'T nmod(T&, U) [with T = long long int; U = int]':
a.cc:188:23:   required from here
  188 |                         trans.fi.se++; nmod(trans.fi.se, INF);
      |                                        ~~~~^~~~~~~~~~~~~~~~~~
a.cc:98:1: warning: no return statement in function returning non-void [-Wreturn-type]
   98 | }
      | ^