@@ -446,6 +446,52 @@ class Solution {
446446 }
447447}
448448```
449+ ``` java
450+ // 解法3 DFS统一迭代法
451+ class Solution {
452+ public List<List<Integer > > pathSum (TreeNode root , int targetSum ) {
453+ List<List<Integer > > result = new ArrayList<> ();
454+ Stack<TreeNode > nodeStack = new Stack<> ();
455+ Stack<Integer > sumStack = new Stack<> ();
456+ Stack<ArrayList<Integer > > pathStack = new Stack<> ();
457+ if (root == null )
458+ return result;
459+ nodeStack. add(root);
460+ sumStack. add(root. val);
461+ pathStack. add(new ArrayList<> ());
462+ 463+ while (! nodeStack. isEmpty()){
464+ TreeNode currNode = nodeStack. peek();
465+ int currSum = sumStack. pop();
466+ ArrayList<Integer > currPath = pathStack. pop();
467+ if (currNode != null ){
468+ nodeStack. pop();
469+ nodeStack. add(currNode);
470+ nodeStack. add(null );
471+ sumStack. add(currSum);
472+ currPath. add(currNode. val);
473+ pathStack. add(new ArrayList (currPath));
474+ if (currNode. right != null ){
475+ nodeStack. add(currNode. right);
476+ sumStack. add(currSum + currNode. right. val);
477+ pathStack. add(new ArrayList (currPath));
478+ }
479+ if (currNode. left != null ){
480+ nodeStack. add(currNode. left);
481+ sumStack. add(currSum + currNode. left. val);
482+ pathStack. add(new ArrayList (currPath));
483+ }
484+ }else {
485+ nodeStack. pop();
486+ TreeNode temp = nodeStack. pop();
487+ if (temp. left == null && temp. right == null && currSum == targetSum)
488+ result. add(new ArrayList (currPath));
489+ }
490+ }
491+ return result;
492+ }
493+ }
494+ ```
449495
450496## python
451497
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