add AllPathsFromSourceToTarget - Day 24

Author: rajeshsantha

src/com/concept/scala/leetcode_30days_challenge_July2020/AllPathsFromSourceToTarget.scala

@@ -0,0 +1,41 @@
+package com.concept.scala.leetcode_30days_challenge_July2020
+
+/** **
+ * Day 24
+ *
+ * @todo Given a directed, acyclic graph of N nodes. Find all possible paths from node 0 to node N-1, and return them in any order.
+ * The graph is given as follows: the nodes are 0, 1, ..., graph.length - 1. graph[i] is a list of all nodes j for which the edge (i, j) exists.
+ * @example Example:
+ * Input: [[1,2], [3], [3], []]
+ * Output: [[0,1,3],[0,2,3]]
+ * Explanation: The graph looks like this:
+ * 0--->1
+ * | |
+ * v v
+ * 2--->3
+ * There are two paths: 0 -> 1 -> 3 and 0 -> 2 -> 3.
+ * @note 1.The number of nodes in the graph will be in the range [2, 15].
+ * 2.You can print different paths in any order, but you should keep the order of nodes inside one path.
+ *
+ */
+object AllPathsFromSourceToTarget {
+ def main(args: Array[String]): Unit = {
+ val graph: Array[Array[Int]] = Array(Array(1, 2), Array(3), Array(3), Array())
+ println(allPathsSourceTarget(graph).mkString(","))
+ }
+
+ /**
+ * 26 / 26 test cases passed.
+ * Status: Accepted
+ * Runtime: 828 ms
+ * Memory Usage: 54.7 MB
+ *
+ */
+ def allPathsSourceTarget(graph: Array[Array[Int]]): List[List[Int]] = {
+
+ def paths(source: Int, target: Int): List[List[Int]] = if (source == target) List(List(target)) else (for (n <- graph(source); p <- paths(n, target)) yield source :: p).toList
+
+ paths(0, graph.length - 1)
+
+ }
+}