To solve this problem, we can use a graph data structure to represent the connections between the source and destination cities. We will create a dictionary where the keys are the source cities and the values are lists of destination cities.

Here are the steps to find the correct order of all the tickets:

1. Read the number of tickets, N, from the input.

2. Create an empty dictionary called "tickets".

3. Iterate N times and for each iteration, do the following:
a. Read the source and destination strings from the input.
b. If the source city is not already a key in the "tickets" dictionary, add it with an empty list as the value.
c. Append the destination city to the list of destinations for the corresponding source city in the "tickets" dictionary.

4. Find the starting city by finding the source city that does not appear as a destination in any of the tickets. Let's call this city "start_city".

5. Create an empty list called "itinerary".

6. Start with "start_city" and do the following until there are no more destinations:
a. Append the current city to the "itinerary" list.
b. Get the list of destinations for the current city from the "tickets" dictionary.
c. If the list is empty, break the loop.
d. Otherwise, set the current city to be the first destination in the list and remove it from the list.

7. Print the "itinerary" list in reverse order to get the correct order of all the tickets.

Here is the implementation in Python:

```python
N = int(input())
tickets = {}

for _ in range(N):
src, dest = input().split()
if src not in tickets:
tickets[src] = []
tickets[src].append(dest)

start_city = None
for src in tickets.keys():
if all(src not in dests for dests in tickets.values()):
start_city = src
break

itinerary = []
current_city = start_city

while True:
itinerary.append(current_city)
destinations = tickets[current_city]
if not destinations:
break
current_city = destinations.pop(0)

print(' '.join(itinerary[::-1]))
```

This code will read the input, find the correct order of all the tickets, and print the itinerary as the output.

Question

To solve this problem, we can use a graph data structure to represent the connections between the source and destination cities. We will create a dictionary where the keys are the source cities and the values are lists of destination cities.

Here are the steps to find the correct order of all the tickets:

1. Read the number of tickets, N, from the input.

2. Create an empty dictionary called "tickets".

3. Iterate N times and for each iteration, do the following:
   a. Read the source and destination strings from the input.
   b. If the source city is not already a key in the "tickets" dictionary, add it with an empty list as the value.
   c. Append the destination city to the list of destinations for the corresponding source city in the "tickets" dictionary.

4. Find the starting city by finding the source city that does not appear as a destination in any of the tickets. Let's call this city "start_city".

5. Create an empty list called "itinerary".

6. Start with "start_city" and do the following until there are no more destinations:
   a. Append the current city to the "itinerary" list.
   b. Get the list of destinations for the current city from the "tickets" dictionary.
   c. If the list is empty, break the loop.
   d. Otherwise, set the current city to be the first destination in the list and remove it from the list.

7. Print the "itinerary" list in reverse order to get the correct order of all the tickets.

Here is the implementation in Python:

```python
N = int(input())
tickets = {}

for _ in range(N):
    src, dest = input().split()
    if src not in tickets:
        tickets[src] = []
    tickets[src].append(dest)

start_city = None
for src in tickets.keys():
    if all(src not in dests for dests in tickets.values()):
        start_city = src
        break

itinerary = []
current_city = start_city

while True:
    itinerary.append(current_city)
    destinations = tickets[current_city]
    if not destinations:
        break
    current_city = destinations.pop(0)

print(' '.join(itinerary[::-1]))
```

This code will read the input, find the correct order of all the tickets, and print the itinerary as the output.

Knowee AI · Accepted Answer