1 class Solution {
2 public:
3 bool isInt(const char * s, int start, int end){
4 if (end < start)
5 return false;
6 if (start<=end && (s[start] == '+' || s[start] == '-'))
7 start++;
8 if (end<start)
9 return false;
10 for (int i = start; i <= end; i++){
11 if (s[i]<'0' || s[i]>'9')
12 return false;
13 }
14 return true;
15 }
16 bool isDouble(const char * s, int start, int end){
17 if (start <= end && (s[start] == '+' || s[start] == '-'))
18 start++;
19 for (int i = start; i <= end; i++){
20 if (s[i] == '.'){
21 if (i + 1 <= end && (s[i + 1] == '-' || s[i + 1] == '+'))
22 return false;
23 if (i == start)
24 return isInt(s, i + 1, end);
25 else if (i == end)
26 return isInt(s, start, i-1);
27 else return isInt(s, start, i - 1) && isInt(s, i + 1, end);
28 }
29 }
30 return isInt(s, start, end);
31 }
32 bool isNumber(const char *s) {
33 // Note: The Solution object is instantiated only once and is reused by each test case.
34 int len = strlen(s);
35 int start = 0, end = len - 1;
36 while (start <= end && (s[start] == ' '))
37 start++;
38 while (end >= start && s[end] == ' ')
39 end--;
40 for (int i = start; i <= end; i++){
41 if (s[i] == 'e' || s[i] == 'E'){
42 return isDouble(s, start, i - 1) && isInt(s, i + 1, end);
43 }
44 }
45 return isDouble(s, start , end);
46 }
47 };
