Java Solution (Basic Calculator) 还没测，晚上回去册

class Count{
	 public int Count(String a){
		int  n = a.length();
		int result = 0;
		int  num = 0;
		int p = 0;
		int L1 = a.indexOf(‘(‘);
		int R1 = a.indexOf(‘)‘);
		String b = a.substring(L1+1,R1-1);
		int op = 0;
		if(L1 >= 0 ) return Count(b) + result;
		else 
		{
			for(int i=0 ;i < n ;i++)
			{
				
				if(‘0‘<(a.charAt(i))&& (a.charAt(i))<‘9‘) num = num*10+num;
				switch(op)
				{
					case 0 : break;
					case 1 : num = num + p ;break;
					case 2 : num = p - num ;break;
					default : break;
				}
				if(a.charAt(i)==‘+‘)
				op = 1;
				else if (a.charAt(i)==‘-‘)
				op = 2 ;
				else
				op = 0;	
				p = num ;
				
			}
			result = num;
			return result;
			
		}

				
				
				
				
			}
}这个鸟玩意用了迭代，其实不太好浪费空间，数据多了还容易死，有人用stack还没研究
这个是600mm的还没看明白
https://leetcode.com/discuss/39454/accepted-infix-postfix-based-solution-explaination-600ms