Leetcode 65:Valid Number

Validate if a given string is numeric.

Some examples:

"0"

 => 

true

" 0.1 "

 => 

true

"abc"

 => 

false

"1 a"

 => 

false

"2e10"

 => 

true

Note: It is intended for the problem statement to be ambiguous. You should gather all requirements up front before implementing one.

想要ac这个问题真的是要历经千辛万苦，不断的根据评测结果修改自己的条件代码，最终才能符合要求。

以下是leetcode大神ac的c++代码，格式条例清晰，供给学习。

class Solution {
public:
bool isNumber(string str) {
int state=0, flag=0; // flag to judge the special case "."
while(str[0]==' ') str.erase(0,1);//delete the prefix whitespace
while(str[str.length()-1]==' ') str.erase(str.length()-1, 1);//delete the suffix whitespace
for(int i=0; i<st
4000
r.length(); i++){
if('0'<=str[i] && str[i]<='9'){
flag=1;
if(state<=2) state=2;
else state=(state<=5)?5:7;
}
else if('+'==str[i] || '-'==str[i]){
if(state==0 || state==3) state++;
else return false;
}
else if('.'==str[i]){
if(state<=2) state=6;
else return false;
}
else if('e'==str[i]){
if(flag&&(state==2 || state==6 || state==7)) state=3;
else return false;
}
else return false;
}
return (state==2 || state==5 || (flag&&state==6) || state==7);
}
};

简而言之，就如同客户需求，需要不断的更改完善，更重要的是自己要相对足够全面，才能成功解决问题。