LeetCode 404 Sum of Left Leaves
Calculate the sum of all left leaves of a given binary tree.
Example:
3
/ \
9 20
/ \
15 7
In this binary tree, there are two left leaves, 9 and 15, so 24 is returned
Perform BFS on the binary tree. If the left child node of a node is a leaf node, add it to the answer. The AC code is as follows:
class Solution {
public:
int sumOfLeftLeaves(TreeNode* root) {
int ans=0;
queue<TreeNode*>q;
q.push(root);
while(!q.empty()){
TreeNode* t=q.front();
q.pop();
if(t){
if(t->left){
q.push(t->left);
if(t->left->left==NULL&&t->left->right==NULL) ans+=t->left->val;
}
if(t->right) q.push(t->right);
}
}
return ans;
}
};