AllPathsFromSourceToTarget797

Author: fluency03

README.md

@@ -53,11 +53,11 @@
 | [Graph](https://github.com/fluency03/leetcode-java/blob/master/src/graph) |
 
 
-# Total: 429
+# Total: 430
 
 |   Easy  |  Medium | Hard | - |
 |:-------:|:-------:|:----:|:-:|
-|   116   |   230   |  69  | 4 |
+|   116   |   231   |  69  | 4 |
 
 
 | Question | Solution | Difficulty |
@@ -467,6 +467,7 @@
 | [771. Jewels and Stones](https://leetcode.com/problems/jewels-and-stones/) | [Solution](https://github.com/fluency03/leetcode-java/blob/master/src/JewelsAndStones771.java) | Easy |
 | [777. Swap Adjacent in LR String](https://leetcode.com/problems/swap-adjacent-in-lr-string/) | [Solution](https://github.com/fluency03/leetcode-java/blob/master/src/SwapAdjacentInLRString777.java) | Medium |
 | [779. K-th Symbol in Grammar](https://leetcode.com/problems/k-th-symbol-in-grammar/) | [Solution](https://github.com/fluency03/leetcode-java/blob/master/src/KthSymbolInGrammar779.java) | Medium |
+| [797. All Paths From Source to Target](https://leetcode.com/problems/all-paths-from-source-to-target/) | [Solution](https://github.com/fluency03/leetcode-java/blob/master/src/AllPathsFromSourceToTarget797.java) | Medium |
 | [783. Minimum Distance Between BST Nodes](https://leetcode.com/problems/minimum-distance-between-bst-nodes/) | [Solution](https://github.com/fluency03/leetcode-java/blob/master/src/MinimumDistanceBetweenBSTNodes783.java) | Easy |
 | [802. Find Eventual Safe States](https://leetcode.com/problems/find-eventual-safe-states/) | [Solution](https://github.com/fluency03/leetcode-java/blob/master/src/FindEventualSafeStates802.java) | Medium |
 | [819. Most Common Word](https://leetcode.com/problems/most-common-word/) | [Solution](https://github.com/fluency03/leetcode-java/blob/master/src/MostCommonWord819.java) | Easy |

src/AllPathsFromSourceToTarget797.java

@@ -0,0 +1,72 @@
+/**
+ * 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 are0, 1, ..., graph.length - 1.
+ * graph[i] is a list of all nodes j for which the edge (i, j) exists.
+ * 
+ * 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:
+ * The number of nodes in the graph will be in the range [2, 15].
+ * You can print different paths in any order, but you should keep the order
+ * of nodes inside one path.
+ */
+
+public class AllPathsFromSourceToTarget797 {
+    public List<List<Integer>> allPathsSourceTarget(int[][] graph) {
+        List<List<Integer>> res = new ArrayList<>();
+        if (graph == null || graph.length == 0) return res;
+        int N = graph.length;
+        backtrace(graph, 0, N-1, new ArrayList<>(), res, N);
+        return res;
+    }
+
+    private void backtrace(int[][] graph, int current, int dest, List<Integer> path, List<List<Integer>> res, int N) {
+        if (current == dest) {
+            path.add(current);
+            res.add(new ArrayList<>(path));
+            path.remove(path.size() - 1);
+            return;
+        }
+        
+        path.add(current);
+        for (int child: graph[current]) {
+            backtrace(graph, child, N-1, path, res, N);
+        }
+        path.remove(path.size() - 1);
+    }
+
+
+    public List<List<Integer>> allPathsSourceTarget2(int[][] graph) {
+        List<List<Integer>> res = new ArrayList<>();
+        if (graph == null || graph.length == 0) return res;
+        int N = graph.length;
+        List<Integer> path = new ArrayList<>();
+        path.add(0);
+        backtrace2(graph, 0, N-1, path, res, N);
+        return res;
+    }
+
+    private void backtrace2(int[][] graph, int current, int dest, List<Integer> path, List<List<Integer>> res, int N) {
+        if (current == dest) {
+            res.add(new ArrayList<>(path));
+            return;
+        }
+
+        for (int child: graph[current]) {
+            path.add(child);
+            backtrace2(graph, child, N-1, path, res, N);
+            path.remove(path.size() - 1);
+        }
+    }
+
+}