LeetCode之All Paths From Source to Target（Kotlin）

問題： 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.

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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.

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方法： 深度優先遍歷，按照數組中存儲的路徑遍歷，遍歷全部的path便可獲得結果。

具體實現：

class AllPathsFromSourceToTarget {
    fun allPathsSourceTarget(graph: Array<IntArray>): List<List<Int>> {
        val result = mutableListOf<List<Int>>()
        val path = mutableListOf<Int>()
        path.add(0)
        dfsSearch(graph, path, result, 0)
        path.remove(0)
        return result
    }

    private fun dfsSearch(graph: Array<IntArray>, path: MutableList<Int>, result: MutableList<List<Int>>, node: Int) {
        if (node == graph.lastIndex) {
            result.add(ArrayList<Int>(path))
            return
        }
        for (nextNode in graph[node]) {
            path.add(nextNode)
            dfsSearch(graph, path, result, nextNode)
            path.remove(nextNode)
        }
    }
}

fun main(args: Array<String>) {
    val arrays = arrayOf(intArrayOf(1,2), intArrayOf(3), intArrayOf(3), intArrayOf())
    val allPathsFromSourceToTarget = AllPathsFromSourceToTarget()
    val result = allPathsFromSourceToTarget.allPathsSourceTarget(arrays)
}
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有問題隨時溝通

具體代碼實現能夠參考Github