class Solution {

public:
    inline void initPos() {
        memset(pos, -1, 128);
    	memset(pos + 48, 1, 10);
    	pos['+'] = pos['-'] = 0;
    	pos['e'] = pos['E'] = 3;
    	pos['.'] = 2;
    	pos[' '] = 4;
    }
    
    bool isNumber(string s) {
    	int state = 0;
    	initPos();
    	for(char c: s)
    		if (!(pos[c] >= 0 && 0 <= (state = trans[state][pos[c]])))
    		    return false;
    	return trans[state][5];
    }

private:
    //	+/- d . e/E space can_accept
    int trans[11][6] = {
    	{  1, 2, 8, -1, 0, 0 },
    	{ -1, 2, 8, -1, -1, 0 },
    	{ -1, 2, 3, 5, 10, 1 },
    	{ -1, 4, -1, 5, 10, 1 },
    	{ -1, 4, -1, 5, 10, 1 },
    	{  6, 7, -1, -1, -1, 0 },
    	{ -1, 7, -1, -1, 10, 0 },
    	{ -1, 7, -1, -1, 10, 1 },
    	{ -1, 9, -1, -1, -1, 0 },
    	{ -1, 9, -1, 5, 10, 1 },
    	{ -1, -1, -1, -1, 10 ,1}
    }; 

    char pos[128];
};