Repeated DNA Sequences

Total Accepted: 32259 Total Submissions: 142733 Difficulty: Medium

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"].

class Solution {
public:
    vector<string> findRepeatedDnaSequences(string s) {
        int s_size = s.size();
        vector<string> res;
        if(s_size<10){
            return res;
        }
        unordered_map<string,pair<bool,bool>> umap;
        string str = s.substr(0,10);
        umap[str] = make_pair(true,false);
        for(int i=10;i<s_size;i++){
            str.erase(str.begin());
            str.push_back(s[i]);
            if(umap[str].first){
                if(!umap[str].second){
                    res.push_back(str);
                    umap[str].second = true;
                }
            }else{
                umap[str] = make_pair(true,false);
            }
        }
        return res;
    }
};

Next challenges: (E) Reverse Bits (M) Sparse Matrix Multiplication (M) Maximum Product of Word Lengths