kopia lustrzana https://github.com/animator/learn-python
Update dynamic-programming.md
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@ -265,8 +265,13 @@ def edit_distance(str1, str2, memo={}):
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str1 = "sunday"
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str2 = "saturday"
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print(f"Edit Distance between '{str1}' and '{str2}' is {edit_distance(str1, str2)}.")
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# Output: Edit Distance between 'sunday' and 'saturday' is 3.
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```
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#### Output
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```
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Edit Distance between 'sunday' and 'saturday' is 3.
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```
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## String Edit Distance Code in Python (Bottom-Up Approach)
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```python
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def edit_distance(str1, str2):
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@ -289,8 +294,13 @@ def edit_distance(str1, str2):
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str1 = "sunday"
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str2 = "saturday"
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print(f"Edit Distance between '{str1}' and '{str2}' is {edit_distance(str1, str2)}.")
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# Output: Edit Distance between 'sunday' and 'saturday' is 3.
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```
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#### Output
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```
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Edit Distance between 'sunday' and 'saturday' is 3.
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```
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## **Complexity Analysis:**
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- **Time Complexity:** O(m * n) where m and n are the lengths of string 1 and string 2 respectively
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- **Space Complexity:** O(m * n) for both top-down and bottom-up approaches
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@ -324,8 +334,14 @@ def matrix_chain_order(p, memo={}):
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p = [1, 2, 3, 4]
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print(f"Minimum number of multiplications is {matrix_chain_order(p)}.")
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# Output: Minimum number of multiplications is 18.
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```
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#### Output
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```
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Minimum number of multiplications is 18.
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```
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## Matrix Chain Multiplication Code in Python (Bottom-Up Approach)
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```python
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def matrix_chain_order(p):
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@ -345,13 +361,17 @@ def matrix_chain_order(p):
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p = [1, 2, 3, 4]
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print(f"Minimum number of multiplications is {matrix_chain_order(p)}.")
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# Output: Minimum number of multiplications is 18.
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```
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#### Output
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```
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Minimum number of multiplications is 18.
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```
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## **Complexity Analysis:**
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- **Time Complexity:** O(n^3) where n is the number of matrices in the chain. For an `array p` of dimensions representing the matrices such that the `i-th matrix` has dimensions `p[i-1] x p[i]`, n is `len(p) - 1`
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- **Space Complexity:** O(n^2) for both top-down and bottom-up approaches
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# 7. Optimal Binary Search Tree
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The Matrix Chain Multiplication finds the optimal way to multiply a sequence of matrices to minimize the number of scalar multiplications.
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@ -362,6 +382,7 @@ The Matrix Chain Multiplication finds the optimal way to multiply a sequence of
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- **Recurrence Relation:** Compute the optimal cost by trying each key as the root and choosing the minimum cost.
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## Optimal Binary Search Tree Code in Python (Top-Down Approach with Memoization)
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```python
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def optimal_bst(keys, freq, memo={}):
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n = len(keys)
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@ -386,9 +407,15 @@ def optimal_bst(keys, freq, memo={}):
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keys = [10, 12, 20]
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freq = [34, 8, 50]
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print(f"Cost of Optimal BST is {optimal_bst(keys, freq)}.")
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# Output: Cost of Optimal BST is 142.
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```
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#### Output
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```
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Cost of Optimal BST is 142.
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```
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## Optimal Binary Search Tree Code in Python (Bottom-Up Approach)
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```python
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def optimal_bst(keys, freq):
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n = len(keys)
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@ -414,12 +441,13 @@ def optimal_bst(keys, freq):
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keys = [10, 12, 20]
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freq = [34, 8, 50]
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print(f"Cost of Optimal BST is {optimal_bst(keys, freq)}.")
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# Output: Cost of Optimal BST is 142.
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```
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## **Complexity Analysis:**
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- **Time Complexity:** O(n^3) where n is the number of keys in the binary search tree.
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- **Space Complexity:** O(n^2) for both top-down and bottom-up approaches
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</br>
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<hr>
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</br>
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#### Output
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```
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Cost of Optimal BST is 142.
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```
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### Complexity Analysis
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- **Time Complexity**: O(n^3) where n is the number of keys in the binary search tree.
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- **Space Complexity**: O(n^2) for both top-down and bottom-up approaches
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