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"].
大神的代码： http://blog.csdn.net/wzy_1988/article/details/44224749
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Native method:
public class Solution {
public List<String> findRepeatedDnaSequences(String s) {
List<String> res = new ArrayList<>();
if(s == null || s.length() < 2)
return res;
HashMap<String, Integer> hm = new HashMap<>();
for(int i = 0; i < s.length() - 9; ++i) {
String temp = s.substring(i, i + 10);
if(hm.containsKey(temp))
hm.put(temp, hm.get(temp) + 1);
else
hm.put(temp, 1);
}
for(Map.Entry<String, Integer> entry: hm.entrySet()) {
if(entry.getValue() > 1)
res.add(entry.getKey());
}
return res;
}
}
但是这种写法浪费了太多的空间。
－－－－－－－－－－－－－－－－－－－－－－－－－－－
Method 2: 利用二进制， 存储整数。
http://segmentfault.com/a/1190000002601702
