Merge pull request #2038 from Lozakaka/patch-2

Update 0112.路径总和.md

problems/0112.路径总和.md

@@ -385,6 +385,42 @@ class solution {
     }
 }
 ```
+```Java 統一迭代法
+    public boolean hasPathSum(TreeNode root, int targetSum) {
+        Stack<TreeNode> treeNodeStack = new Stack<>();
+        Stack<Integer> sumStack = new Stack<>();
+
+        if(root == null)
+            return false;
+        treeNodeStack.add(root);
+        sumStack.add(root.val);
+
+        while(!treeNodeStack.isEmpty()){
+            TreeNode curr = treeNodeStack.peek();
+            int tempsum = sumStack.pop();
+            if(curr != null){
+                treeNodeStack.pop();
+                treeNodeStack.add(curr);
+                treeNodeStack.add(null);
+                sumStack.add(tempsum);
+                if(curr.right != null){
+                    treeNodeStack.add(curr.right);
+                    sumStack.add(tempsum + curr.right.val);
+                }
+                if(curr.left != null){
+                    treeNodeStack.add(curr.left);
+                    sumStack.add(tempsum + curr.left.val);
+                }
+            }else{
+                treeNodeStack.pop();
+                TreeNode temp = treeNodeStack.pop();
+                if(temp.left == null && temp.right == null && tempsum == targetSum)
+                    return true;
+            }
+        }
+        return false;
+    }
+```
 
 ### 0113.路径总和-ii