Row-order traversal and serialization and deserialization of binary trees

1. Serialization of binary tree

Serialization: As shown in the figure, serialize in the preceding order to get the string 1!2!3!4!-1!-1!5!-1!-1!3!-1!-1!, where ! means The end of a value, -1 means the node is empty.

Deserialization: The inverse operation of serialization.

attached code

TreeNode* PreMakeTree(TreeNode* root,int value[])
{
//    ifsizeof(data)/sizeof(int)
    int e=value[k++];
    if(e==-1) root=NULL;
    else{
        root=(TreeNode*)malloc(sizeof(struct TreeNode));
        root->val=e;;
        root->left=PreMakeTree(root->left,value);
        root->right=PreMakeTree(root->right,value);
    }
    return root;
}

void PreOrder(TreeNode* root)
{
    if(root!=NULL) {
        printf("%d!",root->val);
        PreOrder(root->left);
        PreOrder(root->right);
    }else
        printf("-1!");
}

 

2. Hierarchical traversal of binary tree

1. Maintain last and nlast pointers.

2. At the beginning last=root

3. Each time the queue is enqueued, nlast is updated to the current enqueue node

4. When current=last, perform a newline operation and update to nlast at the same time

 

attached code

void LevelOrder1(TreeNode* root)
{
    TreeNode* last;
    TreeNode* nlast;
    queue<TreeNode*> q;
    q.push(root);
    last=root;
    while(!q.empty()){
        TreeNode* current=q.front();
        q.pop();
        printf("%d ",current->val);

        if(current->left!=NULL) {
            q.push(current->left);
            nlast=current->left;
        }
        if(current->right!=NULL) {
            q.push(current->right);
            nlast=current->right;
        }

        if(current==last) {
            printf("\n");
            last=nlast;
        }
    }
}