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pathSum_2-113.java
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pathSum_2-113.java
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/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
// Date: 19-04-27
class Solution {
public List<List<Integer>> pathSum(TreeNode root, int sum) {
List<List<Integer>> ret = new ArrayList<List<Integer>>();
List<Integer> pl = new ArrayList<>();
pathSum1(root, sum, pl, ret);
return ret;
}
// f(root, sum) = f(root.left, sum - root.val)
private void pathSum1(TreeNode root, int sum, List<Integer> pl, List<List<Integer>> ret) {
if (root == null) return;
if (root.left == null && root.right == null) {
if (root.val == sum) {
pl.add(root.val);
ret.add(pl);
return;
} else {
return;
}
}
if (root.left != null) {
List<Integer> ppl = new ArrayList<>(pl);
ppl.add(root.val);
pathSum1(root.left, sum - root.val, ppl, ret);
}
if (root.right != null) {
pl.add(root.val);
pathSum1(root.right, sum - root.val, pl, ret);
}
}
}