Solved 3 easy problems

varunu28 · varunu28 · commit ef6bcea3430a · 2017-11-13T16:08:24.000-08:00
diff --git a/Easy/Binary Tree Level Order Traversal II.java b/Easy/Binary Tree Level Order Traversal II.java
@@ -0,0 +1,31 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode(int x) { val = x; }
+ * }
+ */
+class Solution {
+    public List<List<Integer>> levelOrderBottom(TreeNode root) {
+        List<List<Integer>> ans = new ArrayList<>();
+        if(root == null) return ans;
+        Queue<TreeNode> q = new LinkedList<>();
+        q.add(root);
+        
+        while(q.size()>0) {
+            List<Integer> arr = new ArrayList<>();
+            int size = q.size();
+            for (int i=0;i<size;i++) {
+                TreeNode n = q.poll();
+                arr.add(n.val);
+                if(n.left != null) q.add(n.left);
+                if(n.right != null) q.add(n.right);
+            }
+            ans.add(0, arr);
+        }
+        
+        return ans;
+    }
+}
diff --git a/Easy/Longest Harmonious Subsequence.java b/Easy/Longest Harmonious Subsequence.java
@@ -0,0 +1,20 @@
+class Solution {
+    public int findLHS(int[] nums) {
+        
+        int max = 0;
+        
+        Map<Integer, Integer> map = new HashMap<>();
+        
+        for (int n : nums) {
+            map.put(n, map.getOrDefault(n,0)+1);
+        }
+        
+        for (int key : map.keySet()) {
+            if (map.containsKey(key+1)) {
+                max = Math.max(max, map.get(key) + map.get(key+1));
+            }
+        }
+        
+        return max;
+    }
+}
diff --git a/Easy/Subtree of Another Tree.java b/Easy/Subtree of Another Tree.java
@@ -0,0 +1,32 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode(int x) { val = x; }
+ * }
+ */
+class Solution {
+    public boolean isSubtree(TreeNode s, TreeNode t) {
+        return traverseAndString(s).contains(traverseAndString(t));
+    }
+    
+    public String traverseAndString(TreeNode root) {
+        StringBuilder res = new StringBuilder();
+        traverse(root, res);
+        return res.toString();
+    }
+    
+    public void traverse(TreeNode root, StringBuilder res) {
+        
+        if (root == null) {
+            res.append("-");
+            return;
+        }
+        
+        traverse(root.left, res);
+        traverse(root.right, res);
+        res.append(String.valueOf(root.val) + ",");
+    }
+}
