hdu 2072 单词数 解题报告 strtok函数 字符串流 字典树

hdu 2072 单词数 解题报告 strtok函数 字符串流 字典树

解题报告：有很多写法，每种我都介绍下。
1.用set，istringtream。set是一种容器，往里面插入重复的内容时会自动失效，就做到了去重的效果。这种方法很简单，了解一下就行。

#include<iostream>
#include<math.h>
#include<iomanip>
#include<algorithm>
#include<queue>
#include<cstring>
#include<string>
#include<string.h>
#include<map>
#include<stack>
#include<stdio.h>
#include<cstdio>
#include<stdlib.h>
#include<fstream>
#include<sstream>
#include<set>
#pragma warning(disable:4996)
#define INF 0x3f3f3f3f
#define ll long long
#define PI acos(-1.0)
const int N = 1000010;
const int maxn = 1e9;
using namespace std;

int main()
{
	string s;
	while (getline(cin, s) && s != "#")
	{
		istringstream is(s);
		set<string>st;//set自动去重
		string t;
		while (is >> t)
		{
			st.insert(t);
		}
		cout << st.size() << endl;
	}
}

2.用strtok函数。这个函数是专门用来分解字符串的。在delim中的所有字符都会作为分隔点，可以不只是空格。

#include<iostream>
#include<math.h>
#include<iomanip>
#include<algorithm>
#include<queue>
#include<cstring>
#include<string>
#include<string.h>
#include<map>
#include<stack>
#include<stdio.h>
#include<cstdio>
#include<stdlib.h>
#include<fstream>
#include<sstream>
#include<set>
#pragma warning(disable:4996)
#define INF 0x3f3f3f3f
#define ll long long
#define PI acos(-1.0)
const int N = 1000010;
const int maxn = 1e9;
using namespace std;

int main()
{
	char buf[1024];
	char pound[] = "#";
	char delim[] = " ";
	char* p;
	set<string>st;
	while (gets_s(buf) != NULL)
	{
		if (strcmp(buf, pound) == 0)
			break;
		st.clear();
		p = strtok(buf, delim);
		while (p)
		{
			st.insert(p);
			p = strtok(NULL, delim);
		}
		cout << st.size() << endl;
	}
}

3.用字典树。

#include<iostream>
#include<math.h>
#include<iomanip>
#include<algorithm>
#include<queue>
#include<cstring>
#include<string>
#include<string.h>
#include<map>
#include<stack>
#include<stdio.h>
#include<cstdio>
#include<stdlib.h>
#include<fstream>
#include<sstream>
#include<set>
#pragma warning(disable:4996)
#define INF 0x3f3f3f3f
#define ll long long
#define PI acos(-1.0)
const int N = 1000010;
const int maxn = 1e9;
using namespace std;
struct trie {
	int cnt;
	trie* next[26];
	trie()
	{
		cnt = 0;
		for (int i = 0; i < 26; i++)
		{
			next[i] = NULL;
		}
	}
};
int ans;
trie* root, * temp, * t;
void insert(string str)
{
	t = root;
	for (int i = 0; i < str.length(); i++)
	{
		if (t->next[str[i] - 'a'] == NULL)
		{
			temp = new trie;
			t->next[str[i] - 'a'] = temp;			
		}
		t = t->next[str[i] - 'a'];
	}
	if (!t->cnt)
	{
		t->cnt = 1;
		ans++;
	}
}
int main()
{
	string str;
	while (getline(cin, str))
	{
		ans = 0;
		root = new trie;
		if (str.length() == 1 && str[0] == '#')
			break;
		istringstream is(str);
		string s;
		while (is >> s)
		{
			insert(s);
		}
		printf("%d\n", ans);
	}
}