Saturday, June 8, 2013

Phone number combinations @leetcode

刷题必备书籍Cracking the Coding Interview: 150 Programming Questions and Solutions 

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C++ 学习:The C++ Programming Language, 4th Edition
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创业:The Start-up of You: Adapt to the Future, Invest in Yourself, and Transform Your Career
Given a digit string, return all possible letter combinations that the number could represent.
A mapping of digit to letters (just like on the telephone buttons) is given below.
Input:Digit string "23"
Output: ["ad", "ae", "af", "bd", "be", "bf", "cd", "ce", "cf"].
Note:
Although the above answer is in lexicographical order, your answer could be in any order you want.

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Leetcode 316. Remove Duplicate Letters

 这道题表面问的是如何删除重复,实际在问如何从多个字符选取一个保留,从而让整个字符串按升序排列。那么策略就是对于高顺位的字符比如‘a',就要选靠前位置的保留,而低顺位字符如’z'则应该尽量选取靠后位置保留。 算法大概思路:每看到一个字符,我们要决定是否保留 1. ...