To solve this problem, we can use the concept of a graph and perform a depth-first search (DFS) to find the correct order of the tickets.

First, let's read the input. The first line contains the number of tickets, N. We will store this value in a variable.

Next, we will create an empty dictionary called "graph" to represent the connections between source and destination cities. We will iterate N times and for each ticket, we will read the source and destination strings. We will add an entry in the graph dictionary where the source city is the key and the destination city is the value. If the source city already exists in the dictionary, we will append the destination city to its value list.

After reading all the tickets and populating the graph, we will find the starting city. The starting city is the one that does not appear as a destination in any of the tickets. To do this, we will iterate over the values of the graph dictionary and check if each city appears as a destination. If a city does not appear as a destination, we will store it in a variable called "start_city".

Now, we can perform a depth-first search to find the correct order of the tickets. We will create a helper function called "dfs" that takes the current city as a parameter. Inside the function, we will print the current city and recursively call the dfs function for each destination city connected to the current city. We will also keep track of visited cities to avoid visiting the same city multiple times.

Finally, we will call the dfs function with the start_city as the initial parameter. This will print the entire journey plan (itinerary) of Rohan in the correct order.

Here is the step-by-step solution in code:

```python
# Read the number of tickets
N = int(input())

# Create an empty graph dictionary
graph = {}

# Read the tickets and populate the graph
for _ in range(N):
src, dest = input().split()
if src in graph:
graph[src].append(dest)
else:
graph[src] = [dest]

# Find the starting city
start_city = None
for cities in graph.values():
for city in cities:
if city not in graph:
start_city = city
break

# Perform depth-first search
visited = set()

def dfs(city):
print(city)
visited.add(city)
if city in graph:
for dest in graph[city]:
if dest not in visited:
dfs(dest)

dfs(start_city)
```

This code will print the correct order of the tickets, representing the entire journey plan (itinerary) of Rohan.

Question

To solve this problem, we can use the concept of a graph and perform a depth-first search (DFS) to find the correct order of the tickets.

First, let's read the input. The first line contains the number of tickets, N. We will store this value in a variable.

Next, we will create an empty dictionary called "graph" to represent the connections between source and destination cities. We will iterate N times and for each ticket, we will read the source and destination strings. We will add an entry in the graph dictionary where the source city is the key and the destination city is the value. If the source city already exists in the dictionary, we will append the destination city to its value list.

After reading all the tickets and populating the graph, we will find the starting city. The starting city is the one that does not appear as a destination in any of the tickets. To do this, we will iterate over the values of the graph dictionary and check if each city appears as a destination. If a city does not appear as a destination, we will store it in a variable called "start_city".

Now, we can perform a depth-first search to find the correct order of the tickets. We will create a helper function called "dfs" that takes the current city as a parameter. Inside the function, we will print the current city and recursively call the dfs function for each destination city connected to the current city. We will also keep track of visited cities to avoid visiting the same city multiple times.

Finally, we will call the dfs function with the start_city as the initial parameter. This will print the entire journey plan (itinerary) of Rohan in the correct order.

Here is the step-by-step solution in code:

```python
# Read the number of tickets
N = int(input())

# Create an empty graph dictionary
graph = {}

# Read the tickets and populate the graph
for _ in range(N):
    src, dest = input().split()
    if src in graph:
        graph[src].append(dest)
    else:
        graph[src] = [dest]

# Find the starting city
start_city = None
for cities in graph.values():
    for city in cities:
        if city not in graph:
            start_city = city
            break

# Perform depth-first search
visited = set()

def dfs(city):
    print(city)
    visited.add(city)
    if city in graph:
        for dest in graph[city]:
            if dest not in visited:
                dfs(dest)

dfs(start_city)
```

This code will print the correct order of the tickets, representing the entire journey plan (itinerary) of Rohan.

Knowee AI · Accepted Answer