Create 1786-number-of-restricted-paths-from-first-to-last-node.js

Author: everthis

1786-number-of-restricted-paths-from-first-to-last-node.js

@@ -0,0 +1,118 @@
+/**
+ * @param {number} n
+ * @param {number[][]} edges
+ * @return {number}
+ */
+const countRestrictedPaths = function(n, edges) {
+  const adj = {}
+  const MOD = 10 ** 9 + 7
+  for(let edge of edges) {
+    const [u,v,d] = edge
+    if(adj[u] == null) adj[u] = []
+    if(adj[v] == null) adj[v] = []
+    adj[u].push([v, d])
+    adj[v].push([u, d])
+  }
+  const dist = Array(n + 1).fill(Infinity)
+  dist[n] = 0
+  const pq = new PriorityQueue((a, b) => a[0] < b[0])
+  pq.push([0, n])
+  while(!pq.isEmpty()) {
+    const [d, u] = pq.peek()
+    pq.pop()
+    if(d > dist[u]) continue
+    for(let [v, c] of adj[u]) {
+      if(d + c < dist[v]) {
+        dist[v] = d + c
+        pq.push([dist[v], v])
+      }
+    }
+  }
+    
+  const order = Array(n).fill(0)
+  for(let i = 0; i < n; i++) {
+    order[i] = i + 1
+  }
+    
+  order.sort((u, v) => dist[u] - dist[v])
+  const ans = Array(n + 1).fill(0)
+  ans[n] = 1
+  for(let u of order) {
+    for(let [v, c] of adj[u]) {
+      if(dist[v] > dist[u]) {
+        ans[v] = (ans[v] + ans[u]) % MOD
+      }
+    }
+  }
+    
+  return ans[1]
+};
+
+
+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
+    }
+  }
+}