Leet Code: Valid Number.cpp

class Solution {
public:
    bool isNumber(const char *s) {
        enum InputType{
            INVALID,//0
            SPACE,//1
            DIGIT,//2
            SIGN,//3
            DOT,//4
            EXPONET,//5
            NUM,//6
        };
        int transilationTable[][NUM]={
        //INV SPA DIG SIGN DOT EXPONET
            -1, 0,  1,  8,  4, -1,//state 0
            -1, 3,  1, -1,  2,  6,//state 1
            -1, 3,  2, -1, -1,  6,//state 2
            -1, 3, -1, -1, -1, -1,//state 3
            -1,-1,  5, -1, -1, -1,//state 4
            -1, 3,  5, -1, -1,  6,//state 5
            -1,-1,  7,  9, -1, -1,//state 6
            -1, 3,  7, -1, -1, -1,//state 7
            -1,-1,  1, -1,  4, -1,//state 8
            -1,-1,  7, -1, -1, -1,//state 9
        };
        int state=0;
        int i=0;
        while(s[i]!='\0')
        {
            InputType inputType=INVALID;
            if(isdigit(s[i]))
                inputType=DIGIT;
            else if(isspace(s[i]))
                inputType=SPACE;
            else if('+'==s[i]||'-'==s[i])
                inputType=SIGN;
            else if('.'==s[i])
                inputType=DOT;
            else if('e'==s[i]||'E'==s[i])
                inputType=EXPONET;
            
            state=transilationTable[state][inputType];
            if(-1==state)return false;
            ++i;  
        }
        return state==1||state==2||state==3||state==5||state==7;
    }
};

状态转移图：