Programming challenges are a fantastic way to sharpen your coding skills, learn new techniques, and tackle complex problems. Whether you’re a beginner looking to build confidence or an experienced developer seeking to refine your abilities, these challenges can provide valuable practice and insights. Here are ten programming challenges that can help boost your skills:

**1. Two Sum**

**Problem:** Given an array of integers, return the indices of the two numbers that add up to a specific target.

**Skills Tested:** Array manipulation, hash maps, problem-solving.

**Example:**

python

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def two_sum(nums, target): # Your solution here

**Platforms:** LeetCode, HackerRank

**2. Longest Substring Without Repeating Characters**

**Problem:** Find the length of the longest substring without repeating characters in a given string.

**Skills Tested:** String manipulation, sliding window technique.

**Example:**

python

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def length_of_longest_substring(s): # Your solution here

**Platforms:** LeetCode, CodeSignal

**3. Reverse a Linked List**

**Problem:** Reverse a singly linked list and return the head of the reversed list.

**Skills Tested:** Linked lists, pointers, iterative and recursive approaches.

**Example:**

python

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class ListNode: def __init__(self, val=0, next=None): self.val = val self.next = next def reverse_list(head): # Your solution here

**Platforms:** LeetCode, CodeWars

**4. Merge Intervals**

**Problem:** Given a collection of intervals, merge all overlapping intervals.

**Skills Tested:** Sorting, interval merging.

**Example:**

python

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def merge_intervals(intervals): # Your solution here

**Platforms:** LeetCode, HackerRank

**5. Find the Median of Two Sorted Arrays**

**Problem:** Find the median of two sorted arrays of different sizes.

**Skills Tested:** Binary search, array manipulation, divide and conquer.

**Example:**

python

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def find_median_sorted_arrays(nums1, nums2): # Your solution here

**Platforms:** LeetCode, GeeksforGeeks

**6. Knapsack Problem**

**Problem:** Given weights and values of items, determine the maximum value that can be put in a knapsack of a given capacity.

**Skills Tested:** Dynamic programming, optimization.

**Example:**

python

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def knapsack(weights, values, capacity): # Your solution here

**Platforms:** GeeksforGeeks, TopCoder

**7. Sudoku Solver**

**Problem:** Write a program to solve a Sudoku puzzle by filling the empty cells.

**Skills Tested:** Backtracking, constraint satisfaction.

**Example:**

python

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def solve_sudoku(board): # Your solution here

**Platforms:** LeetCode, CodeWars

**8. Generate Parentheses**

**Problem:** Given n pairs of parentheses, generate all combinations of well-formed parentheses.

**Skills Tested:** Backtracking, recursion.

**Example:**

python

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def generate_parentheses(n): # Your solution here

**Platforms:** LeetCode, GeeksforGeeks

**9. Dijkstra’s Algorithm**

**Problem:** Implement Dijkstra’s algorithm to find the shortest path from a source node to all other nodes in a graph.

**Skills Tested:** Graph algorithms, priority queues.

**Example:**

python

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import heapq def dijkstra(graph, start): # Your solution here

**Platforms:** GeeksforGeeks, TopCoder

**10. Word Ladder**

**Problem:** Given two words (beginWord and endWord), and a dictionary, find the shortest transformation sequence from beginWord to endWord.

**Skills Tested:** Breadth-first search, graph traversal.

**Example:**

python

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def word_ladder(begin_word, end_word, word_list): # Your solution here

**Platforms:** LeetCode, HackerRank

**Conclusion**

Tackling these programming challenges will help you build a strong foundation in various algorithms and data structures, enhance your problem-solving skills, and prepare you for coding interviews. Dive into these problems, practice regularly, and analyze different approaches to become a more proficient and confident programmer.