Merge pull request #1556 from ivanpenaloza/february22

adding algo

Author: ivanpenaloza

src/my_project/interviews/amazon_high_frequency_23/common_algos/two_sum_round_11.py

@@ -0,0 +1,19 @@
+from typing import List, Union, Collection, Mapping, Optional
+from abc import ABC, abstractmethod
+
+class Solution:
+    def twoSum(self, nums: List[int], target: int) -> List[int]:
+
+        answer = dict()
+
+        for k, v in enumerate(nums):
+
+            if v in answer:
+                return [answer[v], k]
+            else:
+                answer[target - v] = k
+
+        return []
+
+        
+

src/my_project/interviews/amazon_high_frequency_23/common_algos/valid_palindrome_round_11.py

@@ -0,0 +1,22 @@
+from typing import List, Union, Collection, Mapping, Optional
+from abc import ABC, abstractmethod
+import re
+
+class Solution:
+    def isPalindrome(self, s: str) -> bool:
+
+        # To lowercase
+        s = s.lower()
+
+        # Remove non-alphanumeric characters
+        s = re.sub(pattern=r'[^a-zA-Z0-9]', repl='', string=s)
+
+        # Determine if s is palindrome or not 
+        len_s = len(s)
+
+        for i in range(len_s//2):
+
+            if s[i] != s[len_s - 1 - i]:
+                return False 
+            
+        return True 

src/my_project/interviews/top_150_questions_round_22/ex_84_number_of_islands.py

@@ -0,0 +1,64 @@
+from typing import List, Union, Collection, Mapping, Optional
+from abc import ABC, abstractmethod
+from collections import deque
+
+class Solution:
+    def numIslands(self, grid: List[List[str]]) -> int:
+        """BFS approach - explores island level by level"""
+
+        if not grid:
+            return 0
+        
+        rows, cols = len(grid), len(grid[0])
+        islands = 0
+
+        def bfs(r: int, c: int):
+            queue = deque([(r,c)])
+            grid[r][c] = '0'
+
+            while queue: 
+                row, col = queue.popleft()
+
+                for dr, dc in [(1,0), (-1,0), (0,1), (0,-1)]:
+                    nr, nc = row + dr, col + dc
+                    if (0 <= nr < rows and 0 <= nc < cols and grid[nr][nc] == '1'):
+                        grid[nr][nc] = '0'
+                        queue.append((nr,nc))
+
+        for r in range(rows):
+            for c in range(cols):
+                if grid[r][c] == '1':
+                    islands += 1
+                    bfs(r,c)
+
+        return islands
+    
+
+    def numIslands_DFS(self, grid: List[List[str]]) -> int:
+        """DFS approach - explores island depth-first"""
+
+        if not grid: 
+            return 0
+        
+        rows, cols = len(grid), len(grid[0])
+        islands = 0
+
+        def dfs(r: int, c: int):
+            if (r < 0 or r >= rows or c < 0 or c >= cols or grid[r][c] == '0'):
+                return 
+            
+            grid[r][c] = '0' 
+
+            dfs(r-1,c)
+            dfs(r+1,c)
+            dfs(r,c-1)
+            dfs(r,c+1)
+
+        for r in range(rows):
+            for c in range(cols):
+                if grid[r][c] == '1':
+                    islands += 1
+                    dfs(r,c)
+
+        return islands
+

src/my_project/interviews_typescript/top_150_questions_round_1/ex_84_number_of_islands.ts

@@ -0,0 +1,25 @@
+let m: number, n: number
+function numIslands(grid: string[][]): number {
+    let count: number = 0
+    if (!grid || !grid[0]) return count 
+    m = grid.length
+    n = grid[0].length
+    for (let i = 0; i < m; i++) {
+      for (let j = 0; j < n; j++) {
+          if (grid[i][j] === "1") {
+              count++
+              dfs(grid, i, j)
+          }
+      }  
+    }
+    return count
+};
+
+function dfs(grid: string[][], i: number, j: number) {
+    if (i >= m || j >= n || i < 0 || j < 0 || grid[i][j] === '0') return
+    grid[i][j] = '0'
+    dfs(grid, i + 1, j)
+    dfs(grid, i - 1, j)
+    dfs(grid, i, j - 1)
+    dfs(grid, i, j + 1)
+}

tests/test_150_questions_round_22/test_84_number_of_islands_round_22.py

@@ -0,0 +1,81 @@
+import unittest
+from src.my_project.interviews.top_150_questions_round_22\
+.ex_84_number_of_islands import Solution
+
+class NumberOfIslandsTescaseCase(unittest.TestCase):
+
+    def test_example_1(self):
+        # Example 1: Single island
+        # Input: grid = [
+        #   ["1","1","1","1","0"],
+        #   ["1","1","0","1","0"],
+        #   ["1","1","0","0","0"],
+        #   ["0","0","0","0","0"]
+        # ]
+        # Output: 1
+        solution = Solution()
+        grid = [
+            ["1", "1", "1", "1", "0"],
+            ["1", "1", "0", "1", "0"],
+            ["1", "1", "0", "0", "0"],
+            ["0", "0", "0", "0", "0"]
+        ]
+        result = solution.numIslands(grid)
+        self.assertEqual(result, 1)
+
+    def test_example_2(self):
+        # Example 2: Three islands
+        # Input: grid = [
+        #   ["1","1","0","0","0"],
+        #   ["1","1","0","0","0"],
+        #   ["0","0","1","0","0"],
+        #   ["0","0","0","1","1"]
+        # ]
+        # Output: 3
+        solution = Solution()
+        grid = [
+            ["1", "1", "0", "0", "0"],
+            ["1", "1", "0", "0", "0"],
+            ["0", "0", "1", "0", "0"],
+            ["0", "0", "0", "1", "1"]
+        ]
+        result = solution.numIslands(grid)
+        self.assertEqual(result, 3)
+
+    def test_example_1_dfs(self):
+        # Example 1: Single island (DFS approach)
+        # Input: grid = [
+        #   ["1","1","1","1","0"],
+        #   ["1","1","0","1","0"],
+        #   ["1","1","0","0","0"],
+        #   ["0","0","0","0","0"]
+        # ]
+        # Output: 1
+        solution = Solution()
+        grid = [
+            ["1", "1", "1", "1", "0"],
+            ["1", "1", "0", "1", "0"],
+            ["1", "1", "0", "0", "0"],
+            ["0", "0", "0", "0", "0"]
+        ]
+        result = solution.numIslands_DFS(grid)
+        self.assertEqual(result, 1)
+
+    def test_example_2_dfs(self):
+        # Example 2: Three islands (DFS approach)
+        # Input: grid = [
+        #   ["1","1","0","0","0"],
+        #   ["1","1","0","0","0"],
+        #   ["0","0","1","0","0"],
+        #   ["0","0","0","1","1"]
+        # ]
+        # Output: 3
+        solution = Solution()
+        grid = [
+            ["1", "1", "0", "0", "0"],
+            ["1", "1", "0", "0", "0"],
+            ["0", "0", "1", "0", "0"],
+            ["0", "0", "0", "1", "1"]
+        ]
+        result = solution.numIslands_DFS(grid)
+        self.assertEqual(result, 3)