leetcode

Dynamic Programming I: Day 19

3 files changed, 58 insertions(+), 0 deletions(-)

diff --git a/ Problems/0072.cpp b/ Problems/0072.cpp

@@ -0,0 +1,19 @@

class Solution {

public:

int minDistance(string word1, string word2) {

int n = word1.size(), m = word2.size();

vector<vector<int>> dp(n + 1, vector<int>(m + 1, 0));

for (int i = 1; i <= n; i++) dp[i][0] = i;

for (int j = 1; j <= m; j++) dp[0][j] = j;

for (int i = 1; i <= n; i++) {

for (int j = 1; j <= m; j++) {

if (word1[i - 1] == word2[j - 1])

dp[i][j] = dp[i - 1][j - 1];

else

dp[i][j] = min(dp[i - 1][j - 1], min(dp[i][j - 1], dp[i - 1][j])) + 1;

}

}

return dp.back().back();

}

};

diff --git a/ Problems/1143.cpp b/ Problems/1143.cpp

@@ -0,0 +1,37 @@

// Top-down DP

class Solution {

int search(const string &text1, const string &text2, int si, int sj,

vector<vector<int>> &dp) {

if (si == text1.size() || sj == text2.size()) return 0;

if (dp[si][sj] != -1) return dp[si][sj];

int len = 0, i = si, j = sj;

while (i < text1.size() && j < text2.size() && text1[i] == text2[j])

i++, j++, len++;

if (i == text1.size() || j == text2.size()) return dp[si][sj] = len;

return dp[si][sj] = len + max(search(text1, text2, i + 1, j, dp),

search(text1, text2, i, j + 1, dp));

}

public:

int longestCommonSubsequence(string text1, string text2) {

vector<vector<int>> dp(text1.size(), vector<int>(text2.size(), -1));

return search(text1, text2, 0, 0, dp);

}

};

// Bottom-up DP

class Solution {

public:

int longestCommonSubsequence(string text1, string text2) {

vector<vector<int>> dp(text1.size() + 1, vector<int>(text2.size() + 1, 0));

for (int i = 0; i < text1.size(); i++)

for (int j = 0; j < text2.size(); j++)

if (text1[i] == text2[j])

dp[i + 1][j + 1] = 1 + dp[i][j];

else

dp[i + 1][j + 1] = max(dp[i + 1][j], dp[i][j + 1]);

return dp.back().back();

}

};

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

@@ -66,6 +66,7 @@ for solving problems. | 0066 | Easy | [Plus One](Problems/0066.cpp) | | 0067 | Easy | [Add Binary](Problems/0067.cpp) | | 0070 | Easy | [Climbing Stairs](Problems/0070.cpp) |

| 0072 | Hard | [Edit Distance](Problems/0072.cpp) |

| 0074 | Medium | [Search a 2D Matrix](Problems/0074.cpp) | | 0075 | Medium | [Sort Colors](Problems/0075.cpp) | | 0077 | Medium | [Combinations](Problems/0077.cpp) |

@@ -322,6 +323,7 @@ for solving problems. | 1099 | Easy | [Replace Elements with Greatest Element on Right Side](Problems/1099.cpp) | | 1129 | Medium | [Shortest Path with Alternating Colors](Problems/1129.cpp) | | 1137 | Easy | [N-th Tribonacci Number](Problems/1137.cpp) |

| 1143 | Medium | [Longest Common Subsequence](Problems/1143.cpp) |

| 1202 | Medium | [Smallest String With Swaps](Problems/1202.cpp) | | 1209 | Medium | [Remove All Adjacent Duplicates in String II](Problems/1209.cpp) | | 1290 | Easy | [Convert Binary Number in a Linked List to Integer](Problems/1290.cpp) |