113 Path Sum II – Medium
Problem:
Given a binary tree and a sum, find all root-to-leaf paths where each path’s sum equals the given sum.
For example: Given the below binary tree and sum = 22,
5
/ \
4 8
/ / \
11 13 4
/ \ / \
7 2 5 1
return
[ [5,4,11,2], [5,8,4,5] ]
Thoughts:
The only addition comparing to the version I of this problem is that instead of returning a boolean value, we need to have the exact path of numbers that has the given sum.
Approach will be very similar but need a ArrayList to keep current potential solution.
Solutions:
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Solution {
public List<List<Integer>> pathSum(TreeNode root, int sum) {
List<List<Integer>> result = new LinkedList<List<Integer>>();
process(root, sum, new LinkedList<Integer>(), result);
return result;
}
private void process(TreeNode node, int sum, List<Integer> curr, List<List<Integer>> result){
if (node == null) {
return;
}
curr.add(node.val);
if (node.left == null && node.right == null & node.val == sum) {
result.add(new LinkedList<Integer>(curr));
}
process(node.left, sum - node.val, curr, result);
process(node.right, sum - node.val, curr, result);
curr.remove(curr.size() - 1);
}
}