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[Problem]
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.
[Analysis]
这题的要点只在于将corner cases考虑周全。实在无法通过OJ的话参考spoiler基本就没问题了。
[Solution]
public class Solution { public int atoi(String str) { str = str.trim(); if (str.length() == 0) { return 0; } int sign = 1; int i = 0; if (str.charAt(0) == ‘+‘) { i++; } if (str.charAt(0) == ‘-‘) { sign = -1; i++; } long result = 0; for (; i < str.length(); i++) { int digit = str.charAt(i) - ‘0‘; if (digit > 9 || digit < 0) { break; } else { if (result > Long.MAX_VALUE/10) { break; } result *= 10; if (result > Long.MAX_VALUE - digit) { break; } result += digit; } } result = result * sign; if (result > Integer.MAX_VALUE) { result = Integer.MAX_VALUE; } else if (result < Integer.MIN_VALUE) { result = Integer.MIN_VALUE; } return (int)result; } }
Leetcode #8 String to Integer (atoi) (E)
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原文地址：http://www.cnblogs.com/zhangqieyi/p/4856614.html
