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problem:
Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.
For example:
Given the below binary tree and sum = 22,
5
/ \
4 8
/ / \
11 13 4
/ \ \
7 2 1
return true, as there exist a root-to-leaf path 5->4->11->2 which sum is 22.
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solution:
// Definition for binary tree
struct TreeNode {
int val;
TreeNode *left;
TreeNode *right;
TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};
bool hasPathSum(TreeNode *root, int sum)
{
if(root == NULL)
return false;
int leftsum = sum - root->val;
if(leftsum == 0 && root->left == NULL && root->right == NULL)
return true;
bool left = hasPathSum(root->left, leftsum);
bool right = hasPathSum(root->right, leftsum);
return left || right;
}