513. 找树左下角的值

513. 找树左下角的值

class Solution {
public:
    int findBottomLeftValue(TreeNode* root) {
        int maxdep=0,res=0;
        help(root,1,maxdep,res);
        return res;
    }
    void help(TreeNode *r,int depth,int &maxdep,int &res){
        if(r==NULL) return;
        if(maxdep<depth) maxdep=depth,res=r->val;
        help(r->left,depth+1,maxdep,res);
        help(r->right,depth+1,maxdep,res);
    }
};