Repeated DNA Sequences

Posted 2020-06-09

package cn.edu.xidian.sselab.hashtable; import java.util.ArrayList; import java.util.HashSet; import java.util.List; import java.util.Set; /**  *  * @author zhiyong wang  * title: Repeated DNA Sequences  * content:  *  All DNA is composed of a series of nucleotides abbreviated as A, C, G, and T,  *  for example: "ACGAATTCCG". When studying DNA, it is sometimes useful to identify repeated sequences within the DNA.  *  Write a function to find all the 10-letter-long sequences (substrings)  *  that occur more than once in a DNA molecule.  *  * For example,  *  * Given s = "AAAAACCCCCAAAAACCCCCCAAAAAGGGTTT",  * Return  * ["AAAAACCCCC", "CCCCCAAAAA"].  *  */ public class RepeatedDNASequences {     //自己很不细心，错了好几个地方（1）自己没有把思路想好，就开始动笔写代码     //（2）上来第一步没有考虑特殊情况     //(3)每次取值范围是（i,i+10）,这两个值都没有注意，直接写的（0,10）     //(4)只考虑了set是否包含，没有考虑set的写入情况     //（5）没有考虑如果存在多个重复，是否要多次插入情况     public List<String> findRepeatedDNASequences(String s){         int length = s.length();         List list = new ArrayList();         if(s == null || length < 10) return list;         Set set = new HashSet();         for(int i=0;i<length-9;i++){             String temp = s.substring(i, i+10);             if(set.contains(temp) && !list.contains(temp)){                 list.add(temp);             }else{                 set.add(temp);             }                      }         return list;     }     public static void main(String[] args) {         RepeatedDNASequences r = new RepeatedDNASequences();         r.findRepeatedDNASequences("CAAAAAAAAAC");     } }