Two-Hundred-Fifty-Eight Commit: Add Same Tree problem to Concurrency section

Author: AAdewunmi

src/Concurrency/Problem_1_Same_Tree.java

@@ -0,0 +1,32 @@
+package Concurrency;
+
+// Problem Statement: Same Tree (medium)
+// LeetCode Question: 100. Same Tree
+
+public class Problem_1_Same_Tree {
+
+    class TreeNode {
+       int val;
+       TreeNode left;
+       TreeNode right;
+       public TreeNode(int val) {
+         this.val = val;
+         this.left = null;
+         this.right = null;
+       }
+    }
+
+    public boolean isSameTree(TreeNode p, TreeNode q) {
+        // p and q are both null
+        if (p == null && q == null) return true;
+        // one of p and q is null
+        if (q == null || p == null) return false;
+        // one of p and q has different value
+        if (p.val != q.val) return false;
+
+        // check left and right subtree recursively
+        return isSameTree(p.right, q.right) &&
+                isSameTree(p.left, q.left);
+    }
+
+}