Create 1743-restore-the-array-from-adjacent-pairs.java

Author: sujal-goswami

Diff for: java/1743-restore-the-array-from-adjacent-pairs.java

@@ -0,0 +1,30 @@
+class Solution {
+    public static int[] restoreArray(int[][] adjacentPairs) {
+        Map<Integer, List<Integer>> g = new HashMap<>();
+        for(int[] p: adjacentPairs){
+            int a = p[0], b = p[1];
+            g.computeIfAbsent(a,val -> new ArrayList<>()).add(b);
+            g.computeIfAbsent(b,val -> new ArrayList<>()).add(a);
+        }
+        int source = 0;
+        for(int node: g.keySet()){
+            if(g.get(node).size() == 1){
+                source = node;
+                break;
+            }
+        }
+        int[] res = new int[adjacentPairs.length+1];
+        Set<Integer> visited = new HashSet<>();
+        dfs(g, source, res, visited, 0);
+        return res;
+    }
+    private static void dfs(Map<Integer, List<Integer>> g, int node, int[] res, Set<Integer> visited, int i){
+        res[i++] = node;
+        visited.add(node);
+        
+        for(int ne: g.get(node)){
+            if(!visited.contains(ne))
+                dfs(g, ne, res, visited, i);
+        }
+    }
+}