Create 882-reachable-nodes-in-subdivided-graph.js

Author: everthis

882-reachable-nodes-in-subdivided-graph.js

@@ -0,0 +1,105 @@
+/**
+ * @param {number[][]} edges
+ * @param {number} M
+ * @param {number} N
+ * @return {number}
+ */
+const reachableNodes = function (edges, M, N) {
+  const graph = Array.from({ length: N }, () => Array(N).fill(-1))
+  for (let edge of edges) {
+    graph[edge[0]][edge[1]] = edge[2]
+    graph[edge[1]][edge[0]] = edge[2]
+  }
+  let result = 0
+  const pq = new PriorityQueue((a, b) => a[1] > b[1])
+  const visited = new Array(N).fill(false)
+  pq.push([0, M])
+  while (!pq.isEmpty()) {
+    const cur = pq.pop()
+    const start = cur[0]
+    const move = cur[1]
+    if (visited[start]) {
+      continue
+    }
+    visited[start] = true
+    result++
+    for (let i = 0; i < N; i++) {
+      if (graph[start][i] > -1) {
+        if (move > graph[start][i] && !visited[i]) {
+          pq.push([i, move - graph[start][i] - 1])
+        }
+        graph[i][start] -= Math.min(move, graph[start][i])
+        result += Math.min(move, graph[start][i])
+      }
+    }
+  }
+  return result
+}
+
+class PriorityQueue {
+  constructor(comparator = (a, b) => a > b) {
+    this.heap = []
+    this.top = 0
+    this.comparator = comparator
+  }
+  size() {
+    return this.heap.length
+  }
+  isEmpty() {
+    return this.size() === 0
+  }
+  peek() {
+    return this.heap[this.top]
+  }
+  push(...values) {
+    values.forEach((value) => {
+      this.heap.push(value)
+      this.siftUp()
+    })
+    return this.size()
+  }
+  pop() {
+    const poppedValue = this.peek()
+    const bottom = this.size() - 1
+    if (bottom > this.top) {
+      this.swap(this.top, bottom)
+    }
+    this.heap.pop()
+    this.siftDown()
+    return poppedValue
+  }
+  replace(value) {
+    const replacedValue = this.peek()
+    this.heap[this.top] = value
+    this.siftDown()
+    return replacedValue
+  }
+
+  parent = (i) => ((i + 1) >>> 1) - 1
+  left = (i) => (i << 1) + 1
+  right = (i) => (i + 1) << 1
+  greater = (i, j) => this.comparator(this.heap[i], this.heap[j])
+  swap = (i, j) => ([this.heap[i], this.heap[j]] = [this.heap[j], this.heap[i]])
+  siftUp = () => {
+    let node = this.size() - 1
+    while (node > this.top && this.greater(node, this.parent(node))) {
+      this.swap(node, this.parent(node))
+      node = this.parent(node)
+    }
+  }
+  siftDown = () => {
+    let node = this.top
+    while (
+      (this.left(node) < this.size() && this.greater(this.left(node), node)) ||
+      (this.right(node) < this.size() && this.greater(this.right(node), node))
+    ) {
+      let maxChild =
+        this.right(node) < this.size() &&
+        this.greater(this.right(node), this.left(node))
+          ? this.right(node)
+          : this.left(node)
+      this.swap(node, maxChild)
+      node = maxChild
+    }
+  }
+}