Topological Sort · Medium

Course Schedule

O(V + E) · O(V + E)

Track node in-degrees and process zero in-degree nodes via BFS queue.

Array Elements & Pointers

[0]

[1]

[2]

[3]

[4]

Live Variables & Invariants

status:Initialized

pattern:Course Schedule

Step 1 / 3

33%

Solution Code

function canFinish(numCourses: number, prerequisites: number[][]): boolean {

  const inDegree = new Array(numCourses).fill(0);

  for (const [a, b] of prerequisites) inDegree[a]++;

  const q: number[] = [];

  for (let i = 0; i < numCourses; i++) if (inDegree[i] === 0) q.push(i);

  let count = 0;

  while (q.length) { const node = q.shift()!; count++; }

  return count === numCourses;

LeetCode IDE Console

3 cases from Blind 75 & NeetCode 150

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