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  • [LeetCode] 65. Valid Number Java

    题目:

    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.

    题意及分析:判断一个字符串是否能转化为合法的数字,主要注意至多只能一个小数点和e,e后面不能有小数点第一位或最后一位可以为小数点,+/-只能出现在第一位或者e后面的第一位。

    代码:

    class Solution {
        public boolean isNumber(String s) {     //判断一个字符串是不是合法的数字
            s = s.trim();
            boolean pointSeen = false;
            boolean eSeen = false;
            boolean isNumber = false;
    
            for(int i=0;i<s.length();i++){
                char temp = s.charAt(i);
                if(temp>='0' && temp<='9'){
                    isNumber = true;
                }else if(temp == '.'){
                    if(eSeen || pointSeen)
                        return false;
                    pointSeen = true;
                }else if(temp == 'e'){
                    if(eSeen || !isNumber)
                        return false;
                    eSeen = true;
                    isNumber = false;
                }else if(temp == '+' || temp=='-'){     //只能在首位或者isNumber后面为+/-
                    if(i!=0 && s.charAt(i-1)!='e' )
                        return false;
                    isNumber = false;
                }else
                    return false;
            }
    
            return isNumber;
        }
    
    }
    

      

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  • 原文地址:https://www.cnblogs.com/271934Liao/p/8244594.html
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