#797. All Paths From Source to Target

Author: papilo-cloud

Backtracking/app_path_source_target.py

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+# Given a directed acyclic graph (DAG) of n nodes labeled from 0 to n - 1,
+# find all possible paths from node 0 to node n - 1 and return them in any order.
+
+# The graph is given as follows: graph[i] is a list of all nodes you can visit from
+# node i (i.e., there is a directed edge from node i to node graph[i][j]).
+
+
+# Example 1:
+# Input: graph = [[1,2],[3],[3],[]]
+# Output: [[0,1,3],[0,2,3]]
+# Explanation: There are two paths: 0 -> 1 -> 3 and 0 -> 2 -> 3.
+
+# Example 2:
+# Input: graph = [[4,3,1],[3,2,4],[3],[4],[]]
+# Output: [[0,4],[0,3,4],[0,1,3,4],[0,1,2,3,4],[0,1,4]]
+ 
+
+# Constraints:
+
+# n == graph.length
+# 2 <= n <= 15
+# 0 <= graph[i][j] < n
+# graph[i][j] != i (i.e., there will be no self-loops).
+# All the elements of graph[i] are unique.
+# The input graph is guaranteed to be a DAG.
+
+
+from typing import List
+class Solution:
+    def allPathsSourceTarget(self, graph: List[List[int]]) -> List[List[int]]:
+        ans = []
+        def dfs(s, path):
+            if len(graph) - 1 == s:
+                ans.append(path)
+                return
+            for i in graph[s]:
+                dfs(i, path+[i])
+        dfs(0, [0])
+        return ans