Redesign the topsort algorithm below so that it selects the last node in each iteration rather than the first. Please use python ad show all work so I can better understand the problem. def topsort(G): count = dict((u, 0) for u in G) for u in G: # The in-degree for each node for v in G[u]: count[v] += 1 Q = [u for u in G if count[u] == 0] S - () while Q: # Count every in-edge # Valid initial nodes # The result # while we have start nodes... # Pick one # Use it as first of the rest u - Q. pop() S. append (u) for v in G[u]: count[v] -- 1 if count[v] == 0: Q.append(v) # "Uncount" its out-edges # New valid start nodes? # Deal with them next return S

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**Topological Sort Algorithm Explanation and Redesign**

This image contains a Python function `topsort(G)` that performs a topological sort on a directed acyclic graph (DAG) represented as a dictionary `G`. The algorithm uses an in-degree method to determine a valid sort order. Here's a detailed breakdown:

### Original Algorithm:

1. **Calculate In-degrees:**
   - The `count` dictionary stores the in-degree (number of incoming edges) for each node. It is initialized by setting each node's count to 0 and then incremented for every incoming edge to that node.

2. **Initialize Queue:**
   - The list `Q` collects nodes with an in-degree of 0. These nodes have no dependencies and can be processed initially.

3. **Process Nodes:**
   - An empty list `S` is initialized to hold the sorted order of nodes.
   - Using a while loop, the algorithm continues while there are nodes in `Q`.
   - Pop a node `u` from `Q`, append it to `S`, and decrement the in-degree of all its neighbors.
   - If any neighbor’s in-degree becomes 0, it is added to `Q` for future processing.

### Requested Modification:

- The task is to redesign the algorithm to select and process the last node in the queue `Q` at each iteration rather than the first.

### Redesigned Algorithm:

To adjust the implementation so that it selects the last node in each iteration:

```python
def topsort(G):
    count = dict((u, 0) for u in G)  # The in-degree for each node
    for u in G:
        for v in G[u]:
            count[v] += 1  # Count every in-edge

    Q = [u for u in G if count[u] == 0]  # Valid initial nodes
    S = []  # The result

    while Q:  # While we have start nodes...
        u = Q.pop()  # Pick the last one
        S.append(u)  # Use it as first of the rest
        for v in G[u]:
            count[v] -= 1  # "Uncount" its out-edges
            if count[v] == 0:  # New valid start nodes?
                Q.append(v)  # Deal with them next

    return S
```

### Explanation of Changes:

- **
Transcribed Image Text:**Topological Sort Algorithm Explanation and Redesign** This image contains a Python function `topsort(G)` that performs a topological sort on a directed acyclic graph (DAG) represented as a dictionary `G`. The algorithm uses an in-degree method to determine a valid sort order. Here's a detailed breakdown: ### Original Algorithm: 1. **Calculate In-degrees:** - The `count` dictionary stores the in-degree (number of incoming edges) for each node. It is initialized by setting each node's count to 0 and then incremented for every incoming edge to that node. 2. **Initialize Queue:** - The list `Q` collects nodes with an in-degree of 0. These nodes have no dependencies and can be processed initially. 3. **Process Nodes:** - An empty list `S` is initialized to hold the sorted order of nodes. - Using a while loop, the algorithm continues while there are nodes in `Q`. - Pop a node `u` from `Q`, append it to `S`, and decrement the in-degree of all its neighbors. - If any neighbor’s in-degree becomes 0, it is added to `Q` for future processing. ### Requested Modification: - The task is to redesign the algorithm to select and process the last node in the queue `Q` at each iteration rather than the first. ### Redesigned Algorithm: To adjust the implementation so that it selects the last node in each iteration: ```python def topsort(G): count = dict((u, 0) for u in G) # The in-degree for each node for u in G: for v in G[u]: count[v] += 1 # Count every in-edge Q = [u for u in G if count[u] == 0] # Valid initial nodes S = [] # The result while Q: # While we have start nodes... u = Q.pop() # Pick the last one S.append(u) # Use it as first of the rest for v in G[u]: count[v] -= 1 # "Uncount" its out-edges if count[v] == 0: # New valid start nodes? Q.append(v) # Deal with them next return S ``` ### Explanation of Changes: - **
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