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Solution.java
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34 lines (29 loc) · 871 Bytes
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package leetCode_437;
/**
* @author dimdark
* @date 2017-09-14
* @time 11:12 AM
*/
public class Solution {
public static class TreeNode {
int val;
TreeNode left, right;
TreeNode(int x) {
this.val = x;
}
}
private int pathCountPerNode(TreeNode root, long sum, long preSum) {
int cnt = 0;
if (root.val + preSum == sum) cnt++;
if (root.left != null) cnt += pathCountPerNode(root.left, sum, preSum+root.val);
if (root.right != null) cnt += pathCountPerNode(root.right, sum, preSum+root.val);
return cnt;
}
public int pathSum(TreeNode root, int sum) {
if (root == null) return 0;
int pathCnt = pathCountPerNode(root, sum, 0);
pathCnt += pathSum(root.left, sum);
pathCnt += pathSum(root.right, sum);
return pathCnt;
}
}