Create 1129-shortest-path-with-alternating-colors.kt

Author: a93a

Diff for: kotlin/1129-shortest-path-with-alternating-colors.kt

@@ -0,0 +1,47 @@
+class Solution {
+    fun shortestAlternatingPaths(n: Int, redEdges: Array<IntArray>, blueEdges: Array<IntArray>): IntArray {
+        val redAdj = Array(n) { ArrayList<Int>() }  
+        val blueAdj = Array(n) { ArrayList<Int>() } 
+        val redVisit = HashSet<Int>()
+        val blueVisit = HashSet<Int>()
+
+        for ((from, to) in redEdges) redAdj[from].add(to) 
+        for ((from, to) in blueEdges) blueAdj[from].add(to) 
+
+        val res = IntArray(n) { -1 }
+
+        with (LinkedList<Pair<Int, Int>>()) {
+            addFirst(0 to 0)
+
+            var len = 0
+            while (isNotEmpty()) {
+                repeat (size) {
+                    val (node, c) = removeLast()
+                    if (res[node] == -1) res[node] = len
+
+                    if (c != -1) {
+                        redAdj[node].forEach {
+                            if (it !in redVisit) {
+                                addFirst(it to -1)
+                                redVisit.add(it)
+                            }
+                        }
+                    }
+
+                    if (c != 1) {
+                        blueAdj[node].forEach {
+                            if (it !in blueVisit) {
+                                addFirst(it to 1)
+                                blueVisit.add(it)
+                            }
+                        }
+                    }
+                }
+
+                len++
+            } 
+        }
+
+        return res
+    }
+}