題目大意:輸入一系列的字串，判斷這些字串中是否存在其中的一個字串是另外一個字串的字首。。

如果是，輸出Set 。。 is not immediately decodable

否則輸出Set .. is immediately decodable

說的通俗點，就是判斷一個字串是否是兩外一個字串的字首

解題思路:

這是一道字典樹的題。一開始的時候，我用c/c++來寫，然後是100行寫完了，就是不知道哪裡錯了

這時，我實在忍不住了。直接就用java來寫了

程式碼如下:(注意以下程式碼在submit的時候是需要對格式改一下的。。。但我這裡可懶得改了)

package com.njupt.acm;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;

public class HDU_1305 {

	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		
		int counter = 1;
		while (scanner.hasNext()) {
			Set set = new HashSet();
			String str = scanner.next();
			boolean flag = true;

			set.add(str);
			while (scanner.hasNext()) {
				str = scanner.next();
				if (str.equals("9")) {
					if(flag){
						System.out.println("Set "+(counter++)+" is immediately decodable");
					}else{
						System.out.println("Set "+(counter++)+" is not immediately decodable");
					}
					break;
				}
				Iterator<String> iter = set.iterator();
				while (iter.hasNext()) {
					String str1 = iter.next();
					if (str.startsWith(str1) || str1.startsWith(str)) {
						flag = false;
						break;
					}
				}
				if(flag){
					set.add(str);
				}
			}
		}
	}
}
 

以下附上讓人心碎的c/c++程式碼

/*
 * 1305_1.cpp
 *
 *  Created on: 2013年8月24日
 *      Author: Administrator
 */

#include <iostream>

using namespace std;

const int maxn = 2;
struct node {
	int count;
	node* next[maxn];
};

node* root;
node* newset() {
	node* current;
	current = (node*) malloc(sizeof(node));

	int i;
	for (i = 0; i < maxn; ++i) {
		current->next[i] = NULL;
	}

	current->count = 1;
	return current;
}

void insert(char* s) {
	node* current;
	int len = strlen(s);
	if (len == 0) {
		return;
	}
	current = root;

	int i;
	for (i = 0; i < len; ++i) {
		if (current->next[s[i] - '0'] != NULL) {
			current = current->next[s[i] - '0'];
			current->count = current->count + 1;
		} else {
			current->next[s[i] - '0'] = newset();
			current = current->next[s[i] - '0'];
		}
	}
}

int find(char* s) {
	node* current;
	int len = strlen(s);
	if (len == 0) {
		return 0;
	}
	current = root;

	int i;
	for (i = 0; i < len; ++i) {
		if (current->next[s[i] - '0'] != NULL) {
			current = current->next[s[i] - '0'];
		} else {
			return 0;
		}
	}

	return current->count;
}

int main() {
	char str[15][15];
		int line = 0, count = 1;

		while (scanf("%s", str[line]) != EOF) {
			root = newset();
			line = 0;
			bool flag = true;
			insert(str[line++]);
			while (scanf("%s", str[line]) != EOF) {
				if (str[line][0] == '9') {
					break;
				}else{
					insert(str[line++]);
				}

			}

			int i;
			for (i = 0; i < line; ++i) {
				if (find(str[i]) > 1) {
					flag = false;
					break;
				}
			}

			if (flag) {
				printf("Set %d is immediately decodable\n", count++);
			} else {
				printf("Set %d is not immediately decodable\n", count++);
			}

		}

		delete root;
}