[Sword refers to Offer learning] [interview 19: Binary Tree image], sword refers to offer

[Sword refers to Offer learning] [interview 19: Binary Tree image], sword refers to offer
Question: complete a function and enter a binary tree. The function outputs its image. Binary Tree node definition:

/*** Tree node of the binary tree */public static class BinaryTreeNode {int value; BinaryTreeNode left; BinaryTreeNode right ;}

Solution:

We previously traverse every node of the tree in order. If the node to be traversed has a child node, we will exchange two of its child nodes. After switching all the left and right subnodes of non-leaf nodes, the tree image is obtained.

Code implementation:

Public class Test19 {/*** Tree node of the binary tree */public static class BinaryTreeNode {int value; BinaryTreeNode left; BinaryTreeNode right;}/*** complete a function and enter... Binary Tree. This function outputs its image ** @ param node root node */public static void mirror (BinaryTreeNode node) {// if the current node is not empty, operate if (node! = Null) {// The following is the BinaryTreeNode tmp = node of the left and right subtree of the exchange node. left; node. left = node. right; node. right = tmp; // process mirror (node. left); mirror (node. right) ;}} public static void printTree (BinaryTreeNode node) {if (node! = Null) {printTree (node. left); System. out. print (node. value + ""); printTree (node. right) ;}} public static void main (String [] args) {// 8 ////// 6 10 /////\// 5 7 9 11 BinaryTreeNode root = new BinaryTreeNode (); root. value = 8; root. left = new BinaryTreeNode (); root. left. value = 6; root. left. left = new BinaryTreeNode (); root. left. left. value = 5; root. left. right = new BinaryTreeNode (); root. left. right. value = 7; root. right = new BinaryTreeNode (); root. right. value = 10; root. right. left = new BinaryTreeNode (); root. right. left. value = 9; root. right. right = new BinaryTreeNode (); root. right. right. value = 11; printTree (root); System. out. println (); mirror (root); printTree (root ); // 1 // 3 // 5 // 7 // 9 BinaryTreeNode root2 = new BinaryTreeNode (); root2.value = 1; root2.left = new BinaryTreeNode (); root2.left. value = 3; root2.left. left = new BinaryTreeNode (); root2.left. left. value = 5; root2.left. left. left = new BinaryTreeNode (); root2.left. left. left. value = 7; root2.left. left. left. left = new BinaryTreeNode (); root2.left. left. left. left. value = 9; System. out. println ("\ n"); printTree (root2); System. out. println (); mirror (root2); printTree (root2 ); // 0 // 2 // 4 // 6 // 8 BinaryTreeNode root3 = new BinaryTreeNode (); root3.value = 0; root3.right = new BinaryTreeNode (); root3.right. value = 2; root3.right. right = new BinaryTreeNode (); root3.right. right. value = 4; root3.right. right. right = new BinaryTreeNode (); root3.right. right. right. value = 6; root3.right. right. right. right = new BinaryTreeNode (); root3.right. right. right. right. value = 8; System. out. println ("\ n"); printTree (root3); System. out. println (); mirror (root3); printTree (root3 );}}

Running result:

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