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LeetCode 1059, Medium. Topics: Graph, Topological Sort, Depth-First Search, Kosaraju. View on LeetCode. Generate this problem as a practice environment: tested reference solution, 12 parametrized pytest cases, and a playground notebook:

Problem

Given the edges of a directed graph where edges[i] = [ai, bi] indicates there is an edge between nodes ai and bi, and two nodes source and destination of this graph, determine whether or not all paths starting from source eventually, end at destination, that is:
  • At least one path exists from the source node to the destination node
  • If a path exists from the source node to a node with no outgoing edges, then that node is equal to destination.
  • The number of possible paths from source to destination is a finite number.
Return true if and only if all roads from source lead to destination.

Examples

Constraints

  • 1 <= n <= 10^4
  • 0 <= edges.length <= 10^4
  • edges[i].length == 2
  • 0 <= ai, bi <= n - 1
  • 0 <= source <= n - 1
  • 0 <= destination <= n - 1
  • The given graph may have self-loops and parallel edges.

Solution

Reference implementation from solution.py on GitHub, full suite in test_solution.py:

Complexity

Tags

NeetCode All.
Last modified on September 7, 2026