AOJ1338.cpp

#include "bits/stdc++.h"
using namespace std;

using VS = vector<string>;    using LL = long long;
using VI = vector<int>;       using VVI = vector<VI>;
using PII = pair<int, int>;   using PLL = pair<LL, LL>;
using VL = vector<LL>;        using VVL = vector<VL>;

#define ALL(a)  begin((a)),end((a))
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define EB emplace_back
#define MP make_pair
#define SZ(a) int((a).size())
#define SORT(c) sort(ALL((c)))
#define RSORT(c) sort(RALL((c)))
#define UNIQ(c) (c).erase(unique(ALL((c))), end((c)))
#define FOR(i, s, e) for (int(i) = (s); (i) < (e); (i)++)
#define FORR(i, s, e) for (int(i) = (s); (i) > (e); (i)--)
#define debug(x) cerr << #x << ": " << x << endl
const int INF = 1e9;                          const LL LINF = 1e16;
const LL MOD = 1000000007;                    const double PI = acos(-1.0);
int DX[8] = { 0, 0, 1, -1, 1, 1, -1, -1 };    int DY[8] = { 1, -1, 0, 0, 1, -1, 1, -1 };

/* -----  2018/06/11  Problem: AOJ 1338 / Link: http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=1338  ----- */
/* ------問題------

A>>B    : A>>B
S<expr> : S*S
で構文解析せよ

-----問題ここまで----- */
/* -----解説等-----
S<S<A>> と、?>>Xみたいのの区別が大変っぽい、
そこで、シフトの方を書き換えることを試みる。
シフトの条件は、 >> TERM
TERM: digit|S
なので、>>S|>>DIGITであるときのみ、この記号を別のものに変えてやれば区別がつく。

----解説ここまで---- */

LL N;

LL ans = 0LL;
LL expr0(int &i, string &s);

LL getnum(int &i, string &s) {
	LL res = 0;
	while (isdigit(s[i])) {
		res *= 10LL;
		res += s[i] - '0';
		i++;
	}
	return res;
}
LL term(int &i, string &s) {
	LL num;
	if (s[i] == 'S') {
		i += 2;// S<
		num = expr0(i, s) % MOD;
		num = (num*num) % MOD;
		i++;// > 
	}
	else num = getnum(i, s);
	return num;
}
// PP, S<expr>
LL expr0(int &i, string &s) {
	LL ret = term(i, s);
	int id = i;
	while (id < SZ(s)) {
		if (s[i] == 'P'&&s[i + 1] == 'P') {
			i += 2;
			ret >>= (min(50LL, term(i, s)));
		}
		else break;
	}
	return ret;
}

int main() {
	cin.tie(0);
	ios_base::sync_with_stdio(false);

	string s;
	while (getline(cin, s)) {
		if (s[0] == '#')break;
		string t;
		FOR(i, 0, SZ(s)) {
			if (s[i] != ' ') {
				t += s[i];
			}
		}// tでやるぞ
		FORR(i, SZ(t) - 3, -1) {
			if (t[i] == '>'&&t[i + 1] == '>' && (t[i + 2] == 'S' || isdigit(t[i + 2]))) {
				t[i] = 'P'; t[i + 1] = 'P';
				int id = i - 1;
				while (0 <= id) {
					if (t[id] == '<')id--;
					else break;
				}
				i = id + 1;
			}
		}
		//cout <<"!!! "<< t << endl;
		int id = 0;
		cout << expr0(id, t) << endl;
	}

	return 0;
}