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Solution.java
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35 lines (29 loc) · 1007 Bytes
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/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Solution {
public boolean hasPathSum(TreeNode root, int sum) {
if (root == null)
return false;
return hasPathSum(root, 0, sum);
}
private boolean hasPathSum(TreeNode node, int pathSum, int expectedSum) {
int currentSum = pathSum + node.val;
if (node.left == null && node.right == null) {
return currentSum == expectedSum;
}
boolean leftHasPathSum = false;
if (node.left != null)
leftHasPathSum = hasPathSum(node.left, currentSum, expectedSum);
boolean rightHasPathSum = false;
if (!leftHasPathSum && node.right != null)
rightHasPathSum = hasPathSum(node.right, currentSum, expectedSum);
return leftHasPathSum || rightHasPathSum;
}
}