404. Sum of Left Leaves

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

Example:

3

/ \
9 20
/ \
15 7

There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24.

/** * Definition for a binary tree node. * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public:    int sum=0;    int sumOfLeftLeaves(TreeNode* root) {        if(root==NULL) return 0;        if(root->left) sumleft(root->left,true);        if(root->right) sumleft(root->right,false);        return sum;    }    void sumleft(TreeNode* root,bool mark){        if(root->left==NULL&&root->right==NULL&&mark==true)            sum+=root->val;        if(root->left) sumleft(root->left,true);        if(root->right) sumleft(root->right,false);    }};