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.

Update (2015-02-10):

The signature of the C++ function had been updated. If you still see your function signature accepts a const char * argument, please click the reload button  to reset your code definition.

思路：此题是真的有些难度的，并且最重要的是我根本就不清楚一个有效数字的规则。。

。

一个连规则都不知道的人怎么能玩好游戏呢，所以果断的挂了10次8次的。最后还是没有全然答对。

临时把别人的代码拿出来放在以下。有时间再好好研究一下：

public class Solution {    public boolean isNumber(String s) {        // Start typing your Java solution below        // DO NOT write main() function       /*               "0" => true        "     0.1     " => true        "abc" => false        "1 a" => false        "+-2e10" => true        //*/        //check input.        if(s==null || s.length()==0) return false;        int sz = s.length();        int i=0;                while(i
     
      ='0' && c<='9') {                number = true;            } else if((c=='+' || c=='-') && neg==false && number==false ) {                neg = true;            } else {                return false;            }        }        return number;    }}