leetcode 019_Valid Parentheses

bool isValid(string s)
{
	int j = 0,n = 0;
	string stack = s;
	while (n != s.size())
	{
		switch (s
)
		{
		case '(':
			stack[j++] = '(';
			break;
		case '[':
			stack[j++] = '[';
			break;
		case '{':
			stack[j++] = '{';
			break;
		case '}':
			if (j > 0 && stack[--j] == '{')
			{
			}	
			else
				return false;
			break;
		case ']':
			if (j > 0 && stack[--j] == '[')
			{
			}
			else
				return false;
			break;
		case ')':
			if (j > 0 && stack[--j] == '(')
			{
			}
			else
				return false;
			break;
		default:
			break;
		}
		++n;
	}
	return (j == 0 );
}