输入一个字符串，并建成一棵二叉树，满足左子树的字符都要小于根结点的字符，右字树的字符都要大于根结点的字符，每个结点值有字符和字符的出现次数，并用三种遍历方法打印，比较是否与自己想象的相一致。再求树的深度、叶子结点数、最大结点值。-Enter a string, and the completion of a binary tree, to meet the characters in the left subtree must be less than the root node of the characters, the characters must be the right word is greater than the tree root node of the characters, the value of each node are emergence of the number of characters and character and use three kinds of traversal methods to print, comparisons are consistent with their own imagination. Again and ask for the depth of leaf nodes, the largest node values.