Leetcode 187: Repeated DNA Sequences (滑动窗口题)

187. Repeated DNA Sequences
     Medium

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’.

解法1：滑动窗口

class Solution {
    
    
public:
    vector<string> findRepeatedDnaSequences(string s) {
    
    
        int n = s.size();
        int left = 0, right = 0;
        string window = "";
        unordered_set<string> windowSet, resSet;
        while (right < n) {
    
    
            char c = s[right];
            window = window + c;
            right++;
            while (left < right && window.size() > 10) {
    
    
                c = s[left];
                window = window.substr(1);
                left++;
            }
            if (window.size() == 10) {
    
    
                if (windowSet.find(window) != windowSet.end()) {
    
    
                    resSet.insert(window);
                } else {
    
    
                    windowSet.insert(window);
                }
            }
        }
        return vector<string>(resSet.begin(), resSet.end());
    }
};