Easy-32

来源：互联网发布：linux 查看nat表编辑：程序博客网时间：2024/06/05 10:58

leetcode 404. Sum of Left Leaves

Find the sum of all left leaves in a given binary tree.

Example:

    3   / \  9  20    /  \   15   7There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24.

AC:

/**
* Definition for a binary tree node.
* struct TreeNode {
*     int val;
*     struct TreeNode *left;
*     struct TreeNode *right;
* };
*/
int travel(struct TreeNode* root,int sign)
{
    if(root==NULL){
        return 0;
    }
    int leftSum=0;
    int rightSum=0;
    if(root->left!=NULL){
        leftSum=travel(root->left,1);
    }
    if(root->right!=NULL){
        rightSum=travel(root->right,2);
    }
    if(sign==1)
    {
        if(root->left!=NULL||root->right!=NULL){
            return leftSum+rightSum;
        }
        return leftSum+rightSum+root->val;
    }
    else
    {
        return leftSum+rightSum;
    }
}
int sumOfLeftLeaves(struct TreeNode* root) {
    int result=travel(root,0);
    return result;
}

tips: 只能加叶子结点的val~

0 0