LeetCode解题报告--String to Integer (atoi)

最新推荐文章于 2020-12-06 02:09:04 发布

置顶 YatKam

最新推荐文章于 2020-12-06 02:09:04 发布

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分类专栏：算法 java LeetCode解题报告 LeetCode 解题报告文章标签： java leetcode 算法字符串整型

本文链接：https://blog.youkuaiyun.com/github_27609763/article/details/46371429

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本文介绍了一种将字符串转换为整数的有效算法实现，并详细解释了处理正负号、去除前后空白字符及防止整数溢出等关键步骤。

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Implement atoi to convert a string to an integer.

Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below and ask yourself what are the possible input cases.

Notes: It is intended for this problem to be specified vaguely (ie, no given input specs). You are responsible to gather all the input requirements up front.
原题出处:https://leetcode.com/problems/string-to-integer-atoi/

public class Solution {
    public int myAtoi(String str) {
            if (str == null || str.length() < 1)
        return 0;

    // trim white spaces
    str = str.trim();
    char flag = '+';

    // check negative or positive
    int i = 0;
    if (str.charAt(0) == '-') {
        flag = '-';
        i++;
    } else if (str.charAt(0) == '+') {
        i++;
    }
    // use double to store result
    double result = 0;

    // calculate value
    while (str.length() > i && str.charAt(i) >= '0' && str.charAt(i) <= '9') 
    {
        result = result * 10 + (str.charAt(i) - '0');
        i++;
    }

    if (flag == '-')
        result = -result;

    // handle max and min
    if (result > Integer.MAX_VALUE)
        return Integer.MAX_VALUE;

    if (result < Integer.MIN_VALUE)
        return Integer.MIN_VALUE;

    return (int) result;
    }
}