LeetCode-Repeated DNA Sequences

LeetCode-Repeated DNA Sequences

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].

采用( s[i] - 'A' + 1 ) % 5 )把A,C,G,T,轉換為1,3,2,0；t = ( (t<<2) & 0xfffff) | ( ( s[i] - 'A' + 1 ) % 5 );進行20位的存貯。

class Solution {
public:
    vector findRepeatedDnaSequences(string s) {
        vector result;
        unordered_map str;
        unordered_map::iterator it;
        int t;
        for (int i = 0; i < s.size() ;i++) {
            t = ( (t<<2) & 0xfffff) | ( ( s[i] - 'A' + 1 ) % 5 );
            if (i < 9)  continue;
            it = str.find(t);
            if (it == str.end())
                str[t] = 1;
            else {
                if (str[t] == 1) {
                    str[t] = 2;
                    result.push_back(s.substr(i-9,10));
                }
            }
        }
        return result;
    }
};