Update 1136-parallel-courses.js

Author: everthis

1136-parallel-courses.js

@@ -1,3 +1,50 @@
+/**
+ * @param {number} n
+ * @param {number[][]} relations
+ * @return {number}
+ */
+const minimumSemesters = function (n, relations) {
+  const inDegree = Array(n + 1).fill(0)
+  const graph = {}
+  for(const [prev, nxt] of relations) {
+    if(graph[prev] == null) graph[prev] = []
+    graph[prev].push(nxt)
+
+    inDegree[nxt]++
+  }
+
+  let q = []
+  for(let i = 1; i <= n; i++) {
+    if(inDegree[i] === 0) q.push(i)
+  }
+
+// console.log(inDegree)
+  let res = 0, cnt = 0
+  while(q.length) {
+    const size = q.length, nxt = []
+
+    for(let i = 0; i < size; i++) {
+      const cur = q[i]
+      for(const e of (graph[cur] || [])) {
+        inDegree[e]--
+        if(inDegree[e] === 0) {
+          nxt.push(e)
+        }
+      }
+    }
+    res++
+    cnt += size
+    q = nxt
+    // console.log(nxt)
+  }
+// console.log(cnt, res)
+
+  return cnt === n ? res : -1
+}
+
+
+// another
+
 /**
  * @param {number} N
  * @param {number[][]} relations