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【Problem】
Unique Characters
Implement an algorithm to determine if a string has all unique characters.
Given "abc", return true.
Given "aab", return false.
What if you can not use additional data structures?
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This problem is from <crack the coding interview>.
It is used to test the basic knowledge of ASCII.
If we didn‘t care about how much space we used, basic idea is to set a flag for every single char in the string. If the char has appeared once, return false.
Following is the code:
public class Solution { /** * @param str: a string * @return: a boolean */ public boolean isUnique(String str) { // write your code here if(str.length()>128) return false; boolean[] char_set= new boolean[256]; for(int i=0;i<str.length();i++) { int val=str.charAt(i); if(char_set[val]) { return false; } else { char_set[val]=true; } } return true; } }
[Lintcode 1 easy]Unique Characters
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原文地址：http://www.cnblogs.com/kittyamin/p/4937975.html
