[Leetcode] 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 shoshould gather all requirements up front before implementing one.

Https://oj.leetcode.com/problems/valid-number/

Train of Thought 1: process it directly. The general idea is to separate integers and decimals according to '.', and then determine each other. The situation is slightly complicated.

Train of Thought 2: automated machine, build a transfer function, and the code is easy to understand.

Idea 3 (lazy): Write the regular expression directly (in fact, the regular expression matching is also an automatic mechanism ).

public class Solution {    public boolean isNumber(String s) {        if (s.trim().isEmpty()) {            return false;        }        String regex = "[-+]?(\\d+\\.?|\\.\\d+)\\d*(e[-+]?\\d+)?";        if (s.trim().matches(regex)) {            return true;        } else {            return false;        }    }    public static void main(String[] args) {        System.out.println(new Solution().isNumber("0"));        System.out.println(new Solution().isNumber("0.1"));        System.out.println(new Solution().isNumber(".1"));        System.out.println(new Solution().isNumber("0."));        System.out.println(new Solution().isNumber("."));        System.out.println(new Solution().isNumber("abc"));        System.out.println(new Solution().isNumber("1 a"));        System.out.println(new Solution().isNumber("2e10"));    }}

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Refer:

Http://jane4532.blogspot.com/2013/09/valid-numberleetcode.html

Http://www.cnblogs.com/chasuner/p/validNumber.html

Http://leetcodenotes.wordpress.com/2013/11/23/leetcode-valid-number/
Http://codeganker.blogspot.com/2014/04/valid-number-leetcode.html