|:------:|:--------:|-------|:---------------:|:------------:|

| 1 |[Two Sum](https://leetcode.com/problems/two-sum/) | Use a hash table to keep track of the indices of the numbers you've encountered so far. | [Python Solution](https://github.com/codethecoffee/leetcode-solutions/blob/master/python_solutions/0001_two_sum.py) | [C++ Solution](https://github.com/codethecoffee/leetcode-solutions/blob/master/c%2B%2B_solutions/0001_two_sum.cpp) |

| 24 | [Swap Nodes in Pairs](https://leetcode.com/problems/swap-nodes-in-pairs/) | Implement both the iterative and recursive solution. What do we do if the linked list has an odd number of nodes? | [Python Solution](https://github.com/codethecoffee/leetcode-solutions/blob/master/python_solutions/0024_swap_nodes_in_pairs.py) | |

| 56 |[Merge Intervals](https://leetcode.com/problems/merge-intervals/)| Sort the intervals by increasing start time. |[Python Solution](https://github.com/codethecoffee/leetcode-solutions/blob/master/python_solutions/0056_merge_intervals.py) | |

| 56 |[Merge Intervals](https://leetcode.com/problems/merge-intervals/)| Sort the intervals by increasing start time. |[Python Solution](https://github.com/codethecoffee/leetcode-solutions/blob/master/python_solutions/0056_merge_intervals.py) | [C++ Solution](https://github.com/codethecoffee/leetcode-solutions/blob/8f2745c473c647ce3f7f8446c7e5215218106b50/c%2B%2B_solutions/0056_merge_intervals.cpp)|

| 66 | [Plus One](https://leetcode.com/problems/plus-one/) | Try iterating through each digit backwards. What do you do when the digit is a 9? | [Python Solution](https://github.com/codethecoffee/leetcode-solutions/blob/master/python_solutions/0066_plus_one.py)| |

| 88 | [Merge Sorted Array](https://leetcode.com/problems/merge-sorted-array/) | Look at one element from each of the arrays, compare them, and make a decision depending on their relation to each other. | [Python Solution](https://github.com/codethecoffee/leetcode-solutions/blob/master/python_solutions/0088_merge_sorted_arrays.py)| |

| 94 | [Binary Tree Inorder Traversal](https://leetcode.com/problems/binary-tree-inorder-traversal/) | Make sure you know how to implement this recursively. The iterative solution is a lot trickier. | [Python Solution](https://github.com/codethecoffee/leetcode-solutions/blob/74ae6c933f170aa828fe2d9833a55ff98a3e6642/python_solutions/0094_binary_tree_inorder_traversal.py)| |

| 102 | [Binary Tree Level Order Traversal](https://leetcode.com/problems/binary-tree-level-order-traversal/) | Keep track of the child nodes of ALL the nodes in the current level. That will be the next level you will traverse. Rinse and repeat until none of the nodes in the current level have children. | [Python Solution](https://github.com/codethecoffee/leetcode-solutions/blob/master/python_solutions/0122_best_time_to_buy_and_sell_stock_II.py) | |

| 122 | [Best Time to Buy and Sell Stock II](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii/solution/) | What should we do every time there is a valley followed by a peak in price? | [Python Solution](https://github.com/codethecoffee/leetcode-solutions/blob/master/python_solutions/0122_best_time_to_buy_and_sell_stock_II.py) | |

| 206 | [Reverse Linked List](https://leetcode.com/problems/reverse-linked-list/) | Try a recursive solution. Split the list up into the first node and the rest of the list. | [Python Solution](https://github.com/codethecoffee/leetcode-solutions/blob/master/python_solutions/0206_reverse_linked_list.py) | |

| 217 | [Contains Duplicate](https://leetcode.com/problems/contains-duplicate/) | Maintain a hash set that keeps track of the numbers we've encountered so far. | [Python Solution](https://github.com/codethecoffee/leetcode-solutions/blob/master/python_solutions/0217_contains_duplicate.py) | |

| 217 | [Contains Duplicate](https://leetcode.com/problems/contains-duplicate/) | Maintain a hash set that keeps track of the numbers we've encountered so far. | [Python Solution](https://github.com/codethecoffee/leetcode-solutions/blob/master/python_solutions/0217_contains_duplicate.py) | [C++ Solution](https://github.com/codethecoffee/leetcode-solutions/blob/8f2745c473c647ce3f7f8446c7e5215218106b50/c%2B%2B_solutions/0217_contains_duplicate.cpp)|

| 344 | [Reverse String](https://leetcode.com/problems/reverse-string) | Use the two pointer approach. Try implementing an iterative and recursive solution. | [Python Solution](https://github.com/codethecoffee/leetcode-solutions/blob/master/python_solutions/0344_reverse_string.py)| |

| 392 | [Is Subsequence](https://leetcode.com/problems/is-subsequence/) | Use two pointers to iterate through the two strings simultaneously. | [Python Solution](https://github.com/codethecoffee/leetcode-solutions/blob/master/python_solutions/0392_is_subsequence.py)| |

| 409 | [Longest Palindrome](https://leetcode.com/problems/longest-palindrome/) | Create a hash table keeping track of the number of occurrences of each character. How many of each can we include in our longest palindrome? | [Python Solution](https://github.com/codethecoffee/leetcode-solutions/blob/master/python_solutions/0409_longest_palindrome.py)| |