Valid Number

class Solution {
public:
    bool isNumber(const char *s) {
        int transition[9][6] = {
            -1,  0,  3,  1,  2, -1,     // next states for state 0
            -1,  8, -1,  1,  4,  5,     // next states for state 1
            -1, -1, -1,  4, -1, -1,     // next states for state 2
            -1, -1, -1,  1,  2, -1,     // next states for state 3
            -1,  8, -1,  4, -1,  5,     // next states for state 4
            -1, -1,  6,  7, -1, -1,     // next states for state 5
            -1, -1, -1,  7, -1, -1,     // next states for state 6
            -1,  8, -1,  7, -1, -1,     // next states for state 7
            -1,  8, -1, -1, -1, -1,     // next states for state 8
        };
        if (s=="") return false;
        int i=0, state=0;
        while (*s!=0) {
            if (*s==' ') i=1;
            else if (*s=='+' || *s=='-') i=2;
            else if (*s>='0' && *s<='9') i=3;
            else if (*s=='.') i=4;
            else if (*s=='e' || *s=='E') i=5;
            else return false;
            state=transition[state][i];
            if (state==-1) return false;
            s++;
        }
        return state==1 || state==4 || state==7 ||state==8;
    }
};