https://leetcode.com/problems/all-paths-from-source-to-target/descrip…

…tion

interview_prep/algorithm/java/ide_handicapped/all_paths_from_source_to_target/Solution.java

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+import java.util.AbstractList;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+class Solution {
+    public List<List<Integer>> allPathsSourceTarget(int[][] graph) {
+        return new AbstractList<List<Integer>>() {
+            private List<List<Integer>> paths;
+
+            public List<Integer> get(final int index) {
+                if (paths == null) {
+                    solve();
+                }
+                return paths.get(index);
+            }
+
+            public int size() {
+                if (paths == null) {
+                    solve();
+                }
+                return paths.size();
+            }
+
+            private void solve() {
+                paths = new ArrayList<>();
+                dfs(
+                        0,
+                        graph.length - 1,
+                        new boolean[graph.length],
+                        new ArrayList<>() {
+                            {
+                                add(0);
+                            }
+                        });
+            }
+
+            private void dfs(int node, int target, boolean[] pass, List<Integer> path) {
+                if (node == target) {
+                    paths.add(new ArrayList<>(path));
+                    return;
+                }
+                for (int v : graph[node]) {
+                    path.add(v);
+                    dfs(v, target, pass, path);
+                    path.remove(path.size() - 1);
+                }
+            }
+        };
+    }
+
+    public static void main(String[] args) {
+        //https://leetcode.com/problems/all-paths-from-source-to-target/description/
+        t1();
+    }
+
+    public static void t1() {
+        final Solution sol = new Solution();
+        final List res = sol.allPathsSourceTarget(new int[][] { 
+            new int[]{1,2},
+            new int[]{3},
+            new int[]{3},
+            new int[]{0}
+        });
+        assert res.contains(Stream.of(0, 1, 3).collect(Collectors.toList()));
+        assert res.contains(Stream.of(0, 2, 3).collect(Collectors.toList()));
+        // System.out.println(res);
+    }
+
+
+
+}