Print the result

Print the cheapest cost.

Print the result

In the final step we add the print_route() function. It calls init_cost and dp_min_cost to print the result.

This completes the project: the user sees the lowest cost with a single function call. All pieces come together.

Output format

print_route() prints the result as an integer. The output shows the lowest cost from the start city to the last city.

This is the single value the project offers to the user. All computation is summarized in this number.

Exercise print_route function

Write print_route(). Call init_cost(), pass it to dp_min_cost, print the result with print. Call print_route() to print 55.

Show example solution

def init_cities():
    # Return city list
    return ['A', 'B', 'C', 'D']
def init_cost():
    # Return cost matrix
    return [[0, 10, 25, 60], [0, 0, 20, 50], [0, 0, 0, 30], [0, 0, 0, 0]]
def dp_min_cost(cost):
    # Find the lowest cost
    n = len(cost)
    dp = [0] * n
    for i in range(1, n):
        best = float('inf')
        for j in range(i):
            cand = dp[j] + cost[j][i]
            if cand < best:
                best = cand
        dp[i] = best
    return dp[n - 1]
def print_route():
    # Print result
    cost = init_cost()
    result = dp_min_cost(cost)
    print(result)
print_route()

Test yourself

What does print_route do?
- Returns city list
- Sorts array
- Returns matrix
- Prints the cost
Show answer

Prints the cost — print_route prints the cost.

dp_min_cost call

cost = init_cost()
result = ____(cost)

Show answer

cost = init_cost()
result = dp_min_cost(cost)

Print the result: match the terms

init_cities

Cities
init_cost

Cost
dp_min_cost

DP
print_route

Print

Next lesson: Multiplication order

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