Merge pull request neetcode-gh#1695 from a93a/743

Create 0743-network-delay-time.kt

kotlin/0743-network-delay-time.kt

@@ -0,0 +1,33 @@
+class Solution {
+ //times[i] == [source, target, weight]
+ fun networkDelayTime(times: Array<IntArray>, n: Int, k: Int): Int {
+ val adjList = ArrayList<ArrayList<Pair<Int,Int>>>(times.size)
+ for(i in 0..n)
+ adjList.add(ArrayList<Pair<Int,Int>>())
+ for(time in times){
+ val (source, target, weight) = time
+ adjList.get(source).add(Pair(target, weight))
+ }
+ //minheap stores [node, weight]
+ val minHeap = PriorityQueue<IntArray>{ edge1: IntArray, edge2: IntArray ->
+ edge1[1] - edge2[1]
+ }
+ val visited = HashSet<Int>()
+ minHeap.add(intArrayOf(k,0))
+ var time = 0 //the max of all the shortest paths
+ while(!minHeap.isEmpty()){
+ val (node, weight) = minHeap.poll()
+ if(visited.contains(node))
+ continue
+ visited.add(node)
+ time = maxOf(time, weight)
+ val listofnodes = adjList.get(node)
+ for(adjacent in listofnodes){
+ val (adjNode, adjWeight) = adjacent
+ if(!visited.contains(adjNode))
+ minHeap.add(intArrayOf(adjNode, adjWeight+weight)) // total path to each adjNode
+ }
+ }
+ return if(visited.size == n) time else -1
+ }
+}