187. Repeated DNA Sequences|Leetcode solution

 187. Repeated DNA Sequences

The DNA sequence is composed of a series of nucleotides abbreviated as 'A', 'C', 'G', and 'T'.

• For example, "ACGAATTCCG" is a DNA sequence.

When studying DNA, it is useful to identify repeated sequences within the DNA.

Given a string s that represents a DNA sequence, return all the 10-letter-long sequences (substrings) that occur more than once in a DNA molecule. You may return the answer in any order.

 

Example 1:

Input: s = "AAAAACCCCCAAAAACCCCCCAAAAAGGGTTT"
Output: ["AAAAACCCCC","CCCCCAAAAA"]

Example 2:

Input: s = "AAAAAAAAAAAAA"
Output: ["AAAAAAAAAA"]

 

Constraints:

• 1 <= s.length <= 105
• s[i] is either 'A', 'C', 'G', or 'T'.

solution:

class Solution {

public:

    vector<string> findRepeatedDnaSequences(string s) {

        

        int size = s.length();

        unordered_map<string, int>umap;

        vector<string>ans;

        if(size <= 10)

            return ans;

        for(int i =0 ; i <= size-10; i++ )

        {

            string t = s.substr(i , 10);

            umap[t]++;

        }

        for(int i =0 ; i < size-10; i++ )

        {

            string t = s.substr(i , 10);

            if(umap[t] > 1)

            {

                ans.push_back(t);

                umap[t] =0;

            }

        }

        return ans;

    }

};