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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解答
其实只要注意叶节点时的处理就可以了。
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* struct TreeNode *left;
* struct TreeNode *right;
* };
*/
int flag = false;
void DFS(struct TreeNode *root, int sum){
if(root == NULL){
return;
}
){
flag = true;
}
DFS(root->left, sum - root->val);
DFS(root->right, sum - root->val);
}
bool hasPathSum(struct TreeNode* root, int sum) {
flag = false;
DFS(root, sum);
return flag;
}