leetcode

Dynamic Programming I: Day 17

3 files changed, 48 insertions(+), 0 deletions(-)

diff --git a/ Problems/0005.cpp b/ Problems/0005.cpp

@@ -0,0 +1,20 @@

class Solution {

const string len(const string &s, int a, int b) {

while (a >= 0 && b < s.size() && s[a] == s[b]) a--, b++;

return s.substr(a + 1, b - a - 1);

}

public:

string longestPalindrome(string s) {

string res = "", t;

s.push_back(' ');

for (int i = 0; i < s.size(); i++) {

t = len(s, i, i);

if (t.size() > res.size()) res = t;

if (s[i] != s[i + 1]) continue;

t = len(s, i, i + 1);

if (t.size() > res.size()) res = t;

}

return res;

}

};

diff --git a/ Problems/0516.cpp b/ Problems/0516.cpp

@@ -0,0 +1,26 @@

class Solution {

int len(const string &s, const int sa, const int sb,

vector<vector<int>> &mem) {

if (mem[sa][sb]) return mem[sa][sb];

int res = 0, a = sa, b = sb;

while (a < b) {

if (s[a] == s[b])

a++, b--, res += 2;

else {

res += max(len(s, a + 1, b, mem), len(s, a, b - 1, mem));

break;

}

}

if (a == b) res++;

mem[sa][sb] = res;

return res;

}

public:

int longestPalindromeSubseq(string s) {

int n = s.size();

vector<vector<int>> mem(n, vector<int>(n));

return len(s, 0, n - 1, mem);

}

};

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

@@ -26,6 +26,7 @@ for solving problems. | 0001 | Easy | [Two Sum](Problems/0001.cpp) | | 0002 | Medium | [Add Two Numbers](Problems/0002.cpp) | | 0003 | Medium | [Longest Substring Without Repeating Characters](Problems/0003.cpp) |

| 0005 | Medium | [Longest Palindromic Substring](Problems/0005.cpp) |

| 0006 | Medium | [Zigzag Conversion](Problems/0006.cpp) | | 0011 | Medium | [Container With Most Water](Problems/0011.cpp) | | 0012 | Medium | [Integer to Roman](Problems/0012.cpp) |

@@ -212,6 +213,7 @@ for solving problems. | 0501 | Easy | [Find Mode in Binary Search Tree](Problems/0501.cpp) | | 0503 | Medium | [Next Greater Element II](Problems/0503.cpp) | | 0509 | Easy | [Fibonacci Number](Problems/0509.cpp) |

| 0516 | Medium | [Longest Palindromic Subsequence](Problems/0516.cpp) |

| 0520 | Easy | [Detect Capital](Problems/0520.cpp) | | 0530 | Easy | [Minimum Absolute Difference in BST](Problems/0530.cpp) | | 0538 | Medium | [Convert BST to Greater Tree](Problems/0538.cpp) |