Cheapest Flights Within K Stops

Problem

Given n cities connected by flights with prices, along with a source, a destination, and a maximum number of stops k, return the cheapest price to travel from source to destination using at most k stops; return -1 if it's not possible.

Examples

Example 1

Input:n = 4, flights = [[0,1,100],[1,2,100],[2,0,100],[1,3,600],[2,3,200]], src = 0, dst = 3, k = 1

Output:700

Constraints

1 <= n <= 100

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How to approach it: the Advanced Graphs pattern

Beyond basic traversal, some graph problems need ordering constraints (topological sort) or weighted shortest paths (Dijkstra, Bellman-Ford, minimum spanning trees).

Look for this pattern when

The problem has ordering or prerequisite constraints ("do X before Y").
Edges have weights or costs and you need the cheapest path, not just any path.

Read the full Advanced Graphs guide →

Video walkthroughs

Original problem on LeetCode ↗