摩斯密码由“-”和“.”组成，而大多数摩斯密码翻译器的原理为对需要解密的字符串和标准串进行每个元素的遍历和比较，时间复杂度很高。而建立一个二叉树，以左子树代表“-”，右子树代表“.”可以节省看空间还可以免去不匹配情况的遍历。两全其美。

注：此程序能够解密/加密的范围为（26个字母、0-9自然数、“-”和“.”）

解密输入格式举例：

-.- .-. .-.. .--- -.-. -... （回车结束，每个字符串之间相隔一个空格）

加密输入格式举例：

Ea18  -.87awraWqE    （回车结束，不分大小写，不分空格）

程序：

#include<stdlib.h>
#include<string.h>
#include<iostream>
#include<fstream>
#define max 7
#define MAX_SIZE 1000
using namespace std;
typedef struct tree {
	char Data;
	char Code[max];
	struct tree* lchild;
	struct tree* rchild;
}Bitree;
Bitree* create(int n);
void Enter(char code[max], char s, Bitree* t);
Bitree* Init_tran(Bitree* t);
void Porder(Bitree* t);
void Getcode(Bitree *t);
void Gocode();

int main() {
	Bitree* t;
	t = create(max);
	t = Init_tran(t);
	int command;
	while (1) {
		cout << "\t***********************************\n"
			<< "\t*             菜单                *\n"
			<< "\t*                                 *\n"
			<< "\t*           1:解密                *\n"
			<< "\t*                                 *\n"
			<< "\t*           2:加密                *\n"
			<< "\t*                                 *\n"
			<< "\t*           3:结束                *\n"
			<< "\t*                                 *\n"
			<< "\t***********************************\n"
			<< "\t请输入操作序号:";
		cin >> command;
		switch (command) {
		case 1:Getcode(t); break;
		case 2: Gocode(); break;
		default:return 0;
		}
	}
}
Bitree* create(int n) {
	if (n) {
		Bitree* t;
		t = (Bitree*)malloc(sizeof(Bitree));
		t->Data = '*';
		t->lchild = create(n - 1);
		t->rchild = create(n - 1);
		return t;
	}
	return NULL;
}
void Enter(char code[max], char s, Bitree* t) {
	Bitree* p;
	p = t;
	for (int i = 0; i < strlen(code); i++) {
		if (code[i] == '-') {
			p = p->lchild;
		}
		else {
			p = p->rchild;
		}
	}
	p->Data = s;
	strcpy_s(p->Code, max, code);
}
Bitree* Init_tran(Bitree* t) {
	char a[38][max];
	strcpy_s(a[0],max, ".-");
	strcpy_s(a[1],max, "-...");
	strcpy_s(a[2],max,"-.-.");
	strcpy_s(a[3], max,"-..");
	strcpy_s(a[4], max,".");
	strcpy_s(a[5], max,"..-.");
	strcpy_s(a[6], max,"--.");
	strcpy_s(a[7], max,"....");
	strcpy_s(a[8], max,"..");
	strcpy_s(a[9],max, ".---");
	strcpy_s(a[10], max,"-.-");
	strcpy_s(a[11], max,".-..");
	strcpy_s(a[12], max,"--");
	strcpy_s(a[13],max, "-.");
	strcpy_s(a[14], max,"---");
	strcpy_s(a[15],max, ".--.");
	strcpy_s(a[16], max,"--.-");
	strcpy_s(a[17], max,".-.");
	strcpy_s(a[18],max, "...");
	strcpy_s(a[19], max,"-");
	strcpy_s(a[20],max, "..-");
	strcpy_s(a[21],max, "...-");
	strcpy_s(a[22],max, ".--");
	strcpy_s(a[23],max, "-..-");
	strcpy_s(a[24], max,"-.--");
	strcpy_s(a[25],max, "--..");
	strcpy_s(a[26], max,"-----");
	strcpy_s(a[27],max, ".----");
	strcpy_s(a[28],max, "..---");
	strcpy_s(a[29],max, "...--");
	strcpy_s(a[30],max, "....-");
	strcpy_s(a[31],max, ".....");
	strcpy_s(a[32],max, "-....");
	strcpy_s(a[33], max,"--...");
	strcpy_s(a[34],max, "---..");
	strcpy_s(a[35], max,"----.");
	strcpy_s(a[36], max,"-....-");
	strcpy_s(a[37], max,".-.-.-");

	Enter(a[0], 'A', t);
	Enter(a[1], 'B', t);
	Enter(a[2], 'C', t);
	Enter(a[3], 'D', t);
	Enter(a[4], 'E', t);
	Enter(a[5], 'F', t);
	Enter(a[6], 'G', t);
	Enter(a[7], 'H', t);
	Enter(a[8], 'I', t);
	Enter(a[9], 'J', t);
	Enter(a[10], 'K', t);
	Enter(a[11], 'L', t);
	Enter(a[12], 'M', t);
	Enter(a[13], 'N', t);
	Enter(a[14], 'O', t);
	Enter(a[15], 'P', t);
	Enter(a[16], 'Q', t);
	Enter(a[17], 'R', t);
	Enter(a[18], 'S', t);
	Enter(a[19], 'T', t);
	Enter(a[20], 'U', t);
	Enter(a[21], 'V', t);
	Enter(a[22], 'W', t);
	Enter(a[23], 'X', t);
	Enter(a[24], 'Y', t);
	Enter(a[25], 'Z', t);
	Enter(a[26], '0', t);
	Enter(a[27], '1', t);
	Enter(a[28], '2', t);
	Enter(a[29], '3', t);
	Enter(a[30], '4', t);
	Enter(a[31], '5', t);
	Enter(a[32], '6', t);
	Enter(a[33], '7', t);
	Enter(a[34], '8', t);
	Enter(a[35], '9', t);
	Enter(a[36], '-', t);
	Enter(a[37], '.', t);
	return t;
}
void Getcode(Bitree *t) {
	Bitree* p;
	char code[MAX_SIZE];
	char ch;
	char str[MAX_SIZE];
	int i = 0; int j = 0;
	getchar();
	cin.getline(code, MAX_SIZE);
	do {
		p = t;
		while (code[i] == '-' || code[i] == '.') {
			if (code[i] == '-') {
				p = p->lchild;
			}
			else {
				p = p->rchild;
			}
			i++;
		}
		str[j]=p->Data;
		j++;
		i++;
	} while (code[i] != '\0'&&code[i-1]!='\0');
	str[j] = '\0';
	cout << str << endl;
	
}
void Porder(Bitree* t) {//递归先序
	if (t)
	{
		printf("%c  ", t->Data);
		Porder(t->lchild);
		Porder(t->rchild);
	}
	return;
}

void Gocode() {
	char a[38][max];
	strcpy_s(a[0], max, ".-");
	strcpy_s(a[1], max, "-...");
	strcpy_s(a[2], max, "-.-.");
	strcpy_s(a[3], max, "-..");
	strcpy_s(a[4], max, ".");
	strcpy_s(a[5], max, "..-.");
	strcpy_s(a[6], max, "--.");
	strcpy_s(a[7], max, "....");
	strcpy_s(a[8], max, "..");
	strcpy_s(a[9], max, ".---");
	strcpy_s(a[10], max, "-.-");
	strcpy_s(a[11], max, ".-..");
	strcpy_s(a[12], max, "--");
	strcpy_s(a[13], max, "-.");
	strcpy_s(a[14], max, "---");
	strcpy_s(a[15], max, ".--.");
	strcpy_s(a[16], max, "--.-");
	strcpy_s(a[17], max, ".-.");
	strcpy_s(a[18], max, "...");
	strcpy_s(a[19], max, "-");
	strcpy_s(a[20], max, "..-");
	strcpy_s(a[21], max, "...-");
	strcpy_s(a[22], max, ".--");
	strcpy_s(a[23], max, "-..-");
	strcpy_s(a[24], max, "-.--");
	strcpy_s(a[25], max, "--..");
	strcpy_s(a[26], max, "-----");
	strcpy_s(a[27], max, ".----");
	strcpy_s(a[28], max, "..---");
	strcpy_s(a[29], max, "...--");
	strcpy_s(a[30], max, "....-");
	strcpy_s(a[31], max, ".....");
	strcpy_s(a[32], max, "-....");
	strcpy_s(a[33], max, "--...");
	strcpy_s(a[34], max, "---..");
	strcpy_s(a[35], max, "----.");
	strcpy_s(a[36], max, "-....-");
	strcpy_s(a[37], max, ".-.-.-");
	char str[MAX_SIZE];
	getchar();
	cin.getline(str, MAX_SIZE);
	int i = 0;
	do {
		if (str[i] >= 97 && str[i] <= 122) {
			str[i] -= 32;
		}
		if (str[i] >= 48 && str[i] <= 57) {
			cout << a[str[i] - 22] << "  ";
		}
		else if (str[i] >= 65 && str[i] <= 90) {
			cout << a[str[i] - 65] << "  ";
		}
		else if (str[i] == '-') {
			cout << a[36] << "  ";
		}
		else {
			cout << a[37] << "  ";
		}
		i++;
	} while (str[i] != '\0' && str[i - 1] != '\0');
	cout << endl;
}