1class Solution {
 2public:
 3    bool isNumber(string s) {
 4        unordered_map<char, int> mp[9];
 5        mp[0][' ']=0; mp[0]['s']=1; mp[0]['d']=2; mp[0]['.']=4;
 6        mp[1]['d']=2; mp[1]['.']=4;
 7        mp[2]['d']=2; mp[2]['.']=3; mp[2]['e']=5; mp[2][' ']=8;
 8        mp[3]['d']=3; mp[3]['e']=5; mp[3][' ']=8;
 9        mp[4]['d']=3;
10        mp[5]['s']=6; mp[5]['d']=7;
11        mp[6]['d']=7;
12        mp[7]['d']=7; mp[7][' ']=8;
13        mp[8][' ']=8;
14
15        int p = 0;
16        char t;
17        for(char c:s){
18            if('0'<=c && c<='9') t = 'd';
19            else if(c=='+' || c=='-') t = 's';
20            else if(c=='e' || c=='E') t = 'e';
21            else t = c;
22
23            if(mp[p].find(t) == mp[p].end()) return false;
24            p = mp[p][t];
25        }
26        return (p==2 || p==3 || p==7 || p==8);
27    }
28};