leetcode

Data Structure II: Day 9

2 files changed, 59 insertions(+), 0 deletions(-)

diff --git a/ Problems/0187.cpp b/ Problems/0187.cpp

@@ -0,0 +1,58 @@

// Left to right

class Solution {

public:

vector<string> findRepeatedDnaSequences(string s) {

if (s.size() <= 10) return {};

unordered_map<string, int> um;

vector<string> res;

string sec = "";

for (int i = 0; i < 10; i++) sec += s[i];

um[sec]++;

for (int i = 10; i < s.size(); i++) {

sec = sec.substr(1) + s[i];

if (um[sec]++ == 1) res.push_back(sec);

}

return res;

}

};

// Right to left

class Solution {

public:

vector<string> findRepeatedDnaSequences(string s) {

if (s.size() <= 10) return {};

unordered_map<string, int> um;

vector<string> res;

string sec = "";

for (int i = s.size() - 1; i >= s.size() - 10; i--) sec = s[i] + sec;

um[sec]++;

for (int i = s.size() - 10 - 1; i >= 0; i--) {

sec.pop_back();

sec = s[i] + sec;

if (um[sec]++ == 1) res.push_back(sec);

}

return res;

}

};

// Bit hacking

class Solution {

public:

vector<string> findRepeatedDnaSequences(string s) {

unordered_map<unsigned, int> um;

vector<string> res;

for (unsigned i = 0, sec = 0; i < s.size(); i++) {

sec = sec << 3 & 0x3FFFFFFF | s[i] & 7;

if (um[sec]++ == 1) res.push_back(s.substr(i - 9, 10));

}

return res;

}

};

diff --git a/ README.md b/ README.md

@@ -132,6 +132,7 @@ for solving problems. | 0167 | Medium | [Two Sum II - Input Array Is Sorted](Problems/0167.cpp) | | 0169 | Easy | [Majority Element](Problems/0169.cpp) | | 0173 | Medium | [Binary Search Tree Iterator](Problems/0173.cpp) |

| 0187 | Medium | [Repeated DNA Sequences](Problems/0187.cpp) |

| 0189 | Medium | [Rotate Array](Problems/0189.cpp) | | 0190 | Easy | [Reverse Bits](Problems/0190.cpp) | | 0191 | Easy | [Number of 1 Bits](Problems/0191.cpp) |