Python solutions to 344 (iterative + recursive) plus massive renaming and reorganization

Author: codethecoffee

.DS_Store

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 # Leetcode Python Solutions
 [Click here](https://docs.google.com/spreadsheets/d/1EmRVQ2KEknTREwNd4-2qbSzScHMvgzDT0yGGT5u-yA8/edit?usp=sharing) for the google spreadsheet
-organizing the questions by category and linked to the solution I wrote for each of them.
+organizing the questions by category and linked to the solution I wrote for each of them. This is always up to date with the README (with the power of a python script and GitHub workflows).
+
+| Number | Question | Hints | Python Solution | C++ Solution |
+|:------:|:--------:|-------|:---------------:|:------------:|
+| 1 |[Two Sum](https://leetcode.com/problems/two-sum/) | [Python Solution](https://github.com/codethecoffee/leetcode-python-solutions/blob/master/1-Two%20Sum.py) | Use a hash table |
+| 56 |[Merge Intervals](https://leetcode.com/problems/merge-intervals/)|[Python Solution](https://github.com/codethecoffee/leetcode-python-solutions/blob/master/56-Merge%20Intervals.py)| Use a stack |
+| 66 | [Plus One](https://leetcode.com/problems/plus-one/) | [Python Solution](https://github.com/codethecoffee/leetcode-python-solutions/blob/master/66-Plus%20One.py)| Try iterating through each digit backwards. What do you do when the digit is a 9? |
+| 88 | [Merge Sorted Array](https://leetcode.com/problems/merge-sorted-array/) | [Python Solution](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. |
+| 122 | [Best Time to Buy and Sell Stock II](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii/solution/) | [Python Solution](https://github.com/codethecoffee/leetcode-python-solutions/blob/master/122-Best%20Time%20to%20Buy%20and%20Sell%20Stock.py)| What should we do every time there is a valley followed by a peak in price? |
+| 344 | [Reverse String](https://leetcode.com/problems/reverse-string) | |

README.md

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+# Link to problem: https://leetcode.com/problems/reverse-string/
+
+# ITERATIVE SOLUTION
+# Time complexity: O(n), Space complexity: O(1)
+def reverseString(s):
+    """
+    Do not return anything, modify s in-place instead.
+    """
+    str_len = len(s)
+    
+    if str_len in {0,1}:
+        return s
+    
+    # Initialize two "pointers"; one at the first char, one at the last char
+    l,r = 0, str_len-1
+    
+    # Swap the characters at the ends of the current substring
+    # until l and r completely converge in the middle
+    while l < r:
+        old_l, old_r = s[l], s[r]
+        s[l], s[r] = old_r, old_l
+        l+=1
+        r-=1
+
+
+# RECURSIVE SOLUTION
+# Time complexity: O(n), Space complexity: O(n) because of the stack space
+
+def reverseHelper(s, l, r):
+    """
+    Recursive helper function to do the work for reversing the string s
+    """
+    # Base case: l and r have converged
+    if l >= r:
+        return
+    
+    # Swap the two characters in place
+    old_l, old_r = s[l], s[r]
+    s[l], s[r] = old_r, old_l
+    
+    # In recursive call, increment l and decrement r
+    # so that they inch closer to the middle of string
+    reverseHelper(s, l+1, r-1)
+
+def reverseString(s):
+    """
+    Do not return anything, modify s in-place instead.
+    """
+    str_len = len(s)
+    l, r = 0, str_len-1
+    
+    reverseHelper(s, l, r)

1-Two Sum.py renamed to python_solutions/0001_two_sum.py

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+# Python script that is run with every new commit made to Github repo.
+# Automatically populates google spreadsheet with contents of README