You are given a binary tree in which each node contains an integer value.
Find the number of paths that sum to a given value.
The path does not need to start or end at the root or a leaf, but it must go downwards (traveling only from parent nodes to child nodes).
The tree has no more than 1,000 nodes and the values are in the range -1,000,000 to 1,000,000.
Example:
root = [10,5,-3,3,2,null,11,3,-2,null,1], sum = 8
10
/ \
5 -3
/ \ \
3 2 11
/ \ \
3 -2 1
Return 3. The paths that sum to 8 are:
1. 5 -> 3
2. 5 -> 2 -> 1
3. -3 -> 11
class Solution {
public int pathSum(TreeNode root, int sum) {
if(root==null) return 0;
int res = path(root,sum)+pathSum(root.right,sum)+pathSum(root.left,sum);
return res;
}
private int path(TreeNode root, int sum) {
int res=0;
if(root==null)
return res ;
if(sum==root.val)
res+=1;
res+=path(root.left,sum-root.val);
res+=path(root.right,sum-root.val);
return res;
}
}