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Easy/PathSum_112.java

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+/**
+ * Path Sum
+ * Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the
+ * path equals the given sum.
+ * For example:Given the below binary tree and sum = 22,
+ *            5
+ *           / \
+ *          4   8
+ *         /   / \
+ *       11  13  4
+ *      /  \      \
+ *     7    2      1
+ *
+ * Tags: Tree Depth-first Search
+ * Similar Problems: (M) Path Sum II (H) Binary Tree Maximum Path Sum (M) Sum Root to Leaf Numbers
+ * @author:chenshuna
+ */
+
+public class PathSum_112 {
+    public static boolean hasPathSum(TreeNode root, int sum) {
+        if(root == null){
+            return false;
+        }
+        if(sum == root.val && root.left == null && root.right == null){
+            return true;
+        }
+        if(root != null){
+            return hasPathSum(root.left, sum - root.val) || hasPathSum(root.right, sum - root.val);
+        }
+        return false;
+    }
+
+    public static void main(String[] args) {
+        TreeNode res = new TreeNode(5);
+        res.left = new TreeNode(4);
+        res.right = new TreeNode(8);
+        res.left.left = new TreeNode(11);
+        res.right.left = new TreeNode(13);
+        res.right.right = new TreeNode(4);
+        res.left.left.left= new TreeNode(7);
+        res.left.left.right= new TreeNode(2);
+        System.out.print(hasPathSum(res, 22));
+    }
+}