leetcode

Solution to some Leetcode problems written in C++
git clone git://git.dimitrijedobrota.com/leetcode.git
Log | Files | Refs | README | LICENSE |
commitd250236243ac338a7918fcea8415b6582353071b
parentb2bae2ea3099a571005e6c8f79bea05941a27e88
authorDimitrije Dobrota <mail@dimitrijedobrota.com>
dateMon, 13 Feb 2023 17:43:38 +0100

Algorithm II: Day 11

Diffstat:
AProblems/0017.cpp|+++++++++++++++++
AProblems/0079.cpp|+++++++++++++++++++++++++++++++++++++++++++++
MREADME.md|++++-
ATemplates/bfs_floodfill_recursive.cpp|+++++++++++++++++++++++++++

4 files changed, 93 insertions(+), 1 deletions(-)

diff --git a/Problems/0017.cpp b/Problems/0017.cpp

@@ -0,0 +1,17 @@

class Solution {
public:
vector<string> letterCombinations(string digits) {
vector<string> um = {"abc", "def", "ghi", "jkl",
"mno", "pqrs", "tuv", "wxyz"},
res = {""};
for (char d : digits) {
vector<string> tmp;
for (char l : um[d - '2'])
for (const string &s : res) tmp.push_back(s + l);
res = tmp;
}
return res.size() > 1 ? res : vector<string>();
}
};

diff --git a/Problems/0079.cpp b/Problems/0079.cpp

@@ -0,0 +1,45 @@

class Solution {
typedef vector<vector<char>> Matrix;
typedef vector<vector<bool>> Marked;
const vector<pair<int, int>> offsets = {
{ 0, 1},
{ 0, -1},
{ 1, 0},
{-1, 0}
};
int n, m;
int valid(int x, int y) { return x >= 0 && x < n && y >= 0 && y < m; }
string word;
bool dfs(const Matrix &mat, Marked &mark, int a, int b, int got) {
if (got == word.size()) return true;
mark[a][b] = true;
for (auto [oa, ob] : offsets) {
int x = a + oa, y = b + ob;
if (!valid(x, y) || mark[x][y] || mat[x][y] != word[got]) continue;
if (dfs(mat, mark, x, y, got + 1)) return true;
}
mark[a][b] = false;
return false;
}
public:
bool exist(const Matrix &board, string word) {
n = board.size(), m = board[0].size();
this->word = word;
Marked visited(n, vector<bool>(m, false));
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
if (board[i][j] != word[0]) continue;
if (dfs(board, visited, i, j, 1)) return true;
}
}
return false;
}
};

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

@@ -17,7 +17,8 @@ for solving problems.

* [MST from edge priority queue](Templates/MST_pq.cpp)
* [MST from edge vector](Templates/MST_vector.cpp)
* [Matrix BFS/Flood fill](Templates/bfs_floodfill.cpp)
* [Matrix BFS/Flood fill Iterative](Templates/bfs_floodfill.cpp)
* [Matrix BFS/Flood fill Recursive](Templates/bfs_floodfill_recursive.cpp)
* [Union Find](Templates/Union_Find.cpp)
## Problems

@@ -34,6 +35,7 @@ for solving problems.

| 0013 | Easy | [Roman to Integer](Problems/0013.cpp) |
| 0014 | Easy | [Longest Common Prefix](Problems/0014.cpp) |
| 0015 | Medium | [3Sum](Problems/0015.cpp) |
| 0017 | Medium | [Letter Combinations of a Phone Number](Problems/0017.cpp) |
| 0019 | Medium | [Remove Nth Node From the End of List](Problems/0019.cpp) |
| 0020 | Easy | [Valid Parentheses](Problems/0020.cpp) |
| 0021 | Easy | [Merge Two Sorted Lists](Problems/0021.cpp) |

@@ -75,6 +77,7 @@ for solving problems.

| 0075 | Medium | [Sort Colors](Problems/0075.cpp) |
| 0077 | Medium | [Combinations](Problems/0077.cpp) |
| 0078 | Medium | [Subsets](Problems/0078.cpp) |
| 0079 | Medium | [Word Search](Problems/0079.cpp) |
| 0082 | Medium | [Remove Duplicates from Sorted List II](Problems/0082.cpp) |
| 0083 | Easy | [Remove Duplicates from Sorted List](Problems/0083.cpp) |
| 0084 | Hard | [Largest Rectangle in Histogram](Problems/0084.cpp) |

diff --git a/Templates/bfs_floodfill_recursive.cpp b/Templates/bfs_floodfill_recursive.cpp

@@ -0,0 +1,27 @@

// Matrix BFS/Flood fill Recursive
typedef vector<vector<int>> Matrix;
typedef vector<vector<bool>> Marked;
const vector<pair<int, int>> offsets = {
{ 0, 1},
{ 0, -1},
{ 1, 0},
{-1, 0}
};
int n, m;
int valid(int x, int y) { return x >= 0 && x < n && y >= 0 && y < m; }
bool dfs(const Matrix &mat, Marked &mark, int a, int b) {
if (got == word.size()) return true;
mark[a][b] = true;
for (auto [oa, ob] : offsets) {
int x = a + oa, y = b + ob;
if (!valid(x, y) || mark[x][y]) continue;
if (dfs(mat, mark, x, y)) return true;
}
mark[a][b] = false;
return false;
}