PAT甲组 1071. Speech Patterns (25)

最新推荐文章于 2023-11-30 06:03:35 发布

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最新推荐文章于 2023-11-30 06:03:35 发布

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分类专栏： PAT甲组文章标签： PAT

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本文介绍了一种算法，用于从给定的文本中找到出现频率最高的单词，并详细说明了实现步骤，包括如何处理大小写敏感性和非字母数字字符。

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1071. Speech Patterns (25)

时间限制

300 ms

内存限制

65536 kB

代码长度限制

16000 B

判题程序

Standard

作者

HOU, Qiming

People often have a preference among synonyms of the same word. For example, some may prefer "the police", while others may prefer "the cops". Analyzing such patterns can help to narrow down a speaker's identity, which is useful when validating, for example, whether it's still the same person behind an online avatar.

Now given a paragraph of text sampled from someone's speech, can you find the person's most commonly used word?

Input Specification:

Each input file contains one test case. For each case, there is one line of text no more than 1048576 characters in length, terminated by a carriage return '\n'. The input contains at least one alphanumerical character, i.e., one character from the set [0-9 A-Z a-z].

Output Specification:

For each test case, print in one line the most commonly occurring word in the input text, followed by a space and the number of times it has occurred in the input. If there are more than one such words, print the lexicographically smallest one. The word should be printed in all lower case. Here a "word" is defined as a continuous sequence of alphanumerical characters separated by non-alphanumerical characters or the line beginning/end.

Note that words are case insensitive.

Sample Input:

Can1: "Can a can can a can?  It can!"

Sample Output:

can 5

题意：给一个字符串，输出其中出现次数最多的词和次数（单词仅由字母和数字组成，字母不分大小写，最后统一小写输出）。

思路：用map存每个单词出现的次数，用非单词构成字符切割单词。PS：可能有连续的非法字符，用while吃光比较合适。有可能出现开头就是非法字符的情况，要判断单词字符串非空才能在map里找它。

↓

#include<cstdio>
#include<cmath>
#include<algorithm>
#include<cstring>
#include<string>
#include<iostream>
#include<map>
#include<vector>
#include<set>
using namespace std;

bool book(char c)//判断是不是有效字符
{
	if(c<='Z'&&c>='A') return true;
	if(c<='z'&&c>='a') return true;
	if(c<='9'&&c>='0') return true;
	return false;
}

map<string,int>mp;
string a,c,ans;
int i;

int main()
{
	getline(cin,a);
	while(i<a.size())
	{
		c.clear();
		while(i<a.size()&&book(a[i])==true)
		{
			if(a[i]<='Z'&&a[i]>='A')
				a[i]+=32;
			c+=a[i];
			i++;
		}
		if(c!="")
		{
			if(mp.find(c)==mp.end())//没有出现过的单词
				mp[c]=1;
			else
				mp[c]++;//出现过，加次数
		}
		while(i<a.size()&&book(a[i])==false)//非法字符
			i++;
	}
	int maxx=-1;
	for(map<string,int>::iterator it=mp.begin();it!=mp.end();it++)
	{
		if(it->second>maxx)
		{
			maxx=it->second;
			ans=it->first;
		}
	}
	cout<<ans<<" "<<maxx<<endl;
	return 0;
}