Binary tree traversal

Binary tree traversal

The first traversal order of the binary tree is: Father-> left son-> right son

The central traversal order is: Left son-> father-> right son

The descending order is as follows: Right son-> left son-> father

 

struct Node {    int value;    Node *left_child;    Node *right_child;    Node () {        left_child = right_child = NULL;    }};bool first = true;void Pre_order(Node *tree) {    if(first) {        cout << tree->value;        first = false;    } else cout << " " << tree->value;    if(tree->left_child != NULL) {        Pre_order(tree->left_child);    }    if(tree->right_child != NULL) {        Pre_order(tree->right_child);    }}void Mid_order(Node *tree) {    if(tree->left_child != NULL) {        Mid_order(tree->left_child);    }    if(first) {        cout << tree->value;        first = false;    } else cout << " " << tree->value;    if(tree->right_child != NULL) {        Mid_order(tree->right_child);    }}void Pos_order(Node *tree) {    if(tree->left_child != NULL) {        Pos_order(tree->left_child);    }    if(tree->right_child != NULL) {        Pos_order(tree->right_child);    }    if(first) {        cout << tree->value;        first = false;    } else cout << " " << tree->value;}