Find the sum of the values of all the left leaf nodes of a binary tree

describe

Find the sum of the values ​​of all the left leaf nodes of a binary tree.

A binary tree node is defined as follows:

struct TreeNode {

    int val;

    struct TreeNode *left;

    struct TreeNode *right;

};

The code of the title part has been completed, you only need to add and submit the following functions:

int sumOfLeftLeaves(struct TreeNode* root);

enter

The input is a number of integers (not more than 512) representing the node element value of a binary tree in sequential representation, where 0 indicates that the corresponding node of the binary tree is empty. Input ends with -1. 

output

Output the sum of the element values ​​of all left leaf nodes.

sample input

1 2 3 4 5 0 0 0 0 6 7 -1

Sample output

10

#include<bits/stdc++.h>
using namespace std;
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
};

int s;
void dfs(TreeNode*root)
{
    if(!root)
        return;
    if(root->left)
    {
        if(!root->left->left&&!root->left->right)
            s+=root->left->val;    
            
        dfs(root->left);
    }
    if(root->right)  
        dfs(root->right);
}
int sumOfLeftLeaves(TreeNode* root)
{
    dfs(root);
    return s;
}

TreeNode*creat()
{
    int front=1,rear=0,x;
    TreeNode*qu[1005],*t,*root=NULL;
    while(scanf("%d",&x)!=EOF,x!=-1)
    {
        if(x==0)
            t=NULL;
        else
        {
            t=new TreeNode;
            t->val=x;
              t->left=NULL;
            t->right=NULL;
        }
        qu[++rear]=t;
        if(rear==1)
            root=t;
        else
        {
            if(t&&qu[front])
            {
                if(rear%2==0)
                    qu[front]->left=t;
                else 
                    qu[front]->right=t;
            }
            if(rear%2==1)
                front++;
        }
    }
    return root;
}
intmain ()
{
    TreeNode*x=creat();
    printf("%d\n",sumOfLeftLeaves(x));
    return 0;
}