这道题一开始TLE,卡了5分钟后，依旧全TLE。

#include <iostream>
#include <cstring>
#include <cstdio>
#include <string>
using namespace std;
const int Maxn = 1e6 + 1;
int main()
{
	register string S;
	cin >> S;
	register int stack[Maxn]/*栈*/, top = 0;
	register int x;
	for(register int tp = 0; tp < S.length(); ++tp)
	{
		register int h = 1;
		x = 0; 
		if('0' <= S[tp] && S[tp] <= '9')
		{
			x = S[tp] - '0';
			while('0' <= S[tp + h] && S[tp + h] <= '9')
			{
				x = (x << 3) + (x << 1) + (S[tp + h] - '0');
				x %= 1000;
			}
			tp += h;
		}
		if(S[tp] == '*')
		{
			while(S[tp] == '*')
			{
				++tp;
				h = 1;
				int p;
				p = S[tp] - '0';
				while('0' <= S[tp + h] && S[tp + h] <= '9')
				{
					p = (p << 3) + (p << 1) + (S[tp + h] - '0');
					p %= 1000;
				}
				stack[++top] = (p * x) % 1000;
				tp += h;
			}
		}
		else
		{
			stack[++top] = x;
			x = 0;
		}
	}
	register int ans = 0;
	for(int i = 1; i <= top; i++)
	{
		ans += stack[i];
		ans %= 1000;
	}
	printf("%d\n", ans);
	return 0;
}