[LeetCode] 65. Valid Number

SoapEye 发布于2019-08-16 13:48 / 2865人阅读

Problem

Validate if a given string can be interpreted as a decimal number.

Some examples:

</>复制代码 
"0" => true
" 0.1 " => true
"abc" => false
"1 a" => false
"2e10" => true
" -90e3   " => true
" 1e" => false
"e3" => false
" 6e-1" => true
" 99e2.5 " => false
"53.5e93" => true
" --6 " => false
"-+3" => false
"95a54e53" => false

Note: It is intended for the problem statement to be ambiguous. You should gather all requirements up front before implementing one. However, here is a list of characters that can be in a valid decimal number:

</>复制代码 
Numbers 0-9
Exponent - "e"
Positive/negative sign - "+"/"-"
Decimal point - "."

Of course, the context of these characters also matters in the input.

Solution

</>复制代码 
class Solution {
    public boolean isNumber(String s) {
        if (s == null || s.length() == 0) return false;
        
        s = s.trim();
        int len = s.length();
        if (len == 0) return false;
        
        int signCount = 0;
        boolean hasE = false;
        boolean hasNum = false;
        boolean hasPoint = false;
        
        for (int i = 0; i < len; i++) {
            char ch = s.charAt(i);
            
            if (ch >= "0" && ch <= "9") {
                hasNum = true;
            } else if (ch == "e" || ch == "E") {
                if (hasE || !hasNum || i == len-1) return false;
                hasE = true;
            } else if (ch == ".") {
                if (hasPoint || hasE) return false;
                //0. is true
                if (i == len-1 && !hasNum) return false;
                hasPoint = true;
            } else if (ch == "+" || ch == "-") {
                //two signs at most; should not appear in the end
                if (signCount == 2 || i == len-1) return false;
                //sign appears in the middle but no E/e
                if (i > 0 && !hasE) return false;
                signCount++;
            } else return false;
        }
        
        return true;
    }
}

GPU云服务器云服务器 LeetCode Valid valid?file LeetCode_String

文章版权归作者所有，未经允许请勿转载,若此文章存在违规行为，您可以联系管理员删除。

转载请注明本文地址：https://www.ucloud.cn/yun/72364.html

leetcode65 valid number 正则表达式的运用

摘要：完整的正则表达式为。代码如下翻译如果我们看到数字，就将设为如果看到小数点，则判断是否已有小数点或是，因为后只能有整数只能遇到一次，如果第一次遇到但是没有遇到数字，则返回错误。题目要求 Validate if a given string is numeric. Some examples: 0 => true 0.1 => true abc => false 1 a => fa...

DobbyKim 2019-08-15 10:37 评论0 收藏0
LeetCode65. Valid Number -- 判断合法数字

摘要：描述分析该题的说明比较模糊，所以需要慢慢进行尝试来弄清楚哪些是合法的数字。代码去除前后的空格小数点前面不能出现和小数点前面不能出现，并且需要有数字保证后面也有数字符号只能再位和后面一位描述 Validate if a given string is numeric. Some examples:0 => true 0.1 => trueabc => false1 a => fals...

jindong 2019-07-30 16:57 评论0 收藏0
leetcode部分题目答案之JavaScript版

摘要：自己没事刷的一些的题目，若有更好的解法，希望能够一起探讨项目地址自己没事刷的一些LeetCode的题目，若有更好的解法，希望能够一起探讨 Number Problem Solution Difficulty 204 Count Primes JavaScript Easy 202 Happy Number JavaScript Easy 190 Reverse Bi...

alphahans 2019-08-21 16:20 评论0 收藏0
[LeetCode] 611. Valid Triangle Number

Problem Given an array consists of non-negative integers, your task is to count the number of triplets chosen from the array that can make triangles if we take them as side lengths of a triangle.Examp...

anonymoussf 2019-08-19 11:14 评论0 收藏0
LeetCode 306. Additive Number

摘要：描述累加数是一个字符串，组成它的数字可以形成累加序列。一个有效的累加序列必须至少包含个数。说明累加序列里的数不会以开头，所以不会出现或者的情况。示例输入输出解释累加序列为。 LeetCode 306. Additive Number Description Additive number is a string whose digits can form additive sequen...

GeekQiaQia 2019-07-31 10:03 评论0 收藏0