poj2550&&zcmu1867——Zipf's Law

2019-11-11 04:17:08

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Zipf's Law

Time Limit: 3000MS		Memory Limit: 65536K
Total Submissions: 1812		Accepted: 546

Description

Harvard linguistics PRofessor George Kingsley Zipf (1902-1950) observed that the frequency of the kth most common Word in a text is roughly proportional to 1/k. He justified his observations in a book titled Human behavior and the principle of least effort published in 1949. While Zipf's rationale has largely been discredited, the principle still holds, and others have afforded it a more sound mathematical basis. You are to find all the words occurring n times in an English text. A word is a sequence of letters. Words are separated by non-letters. Capitalization should be ignored. A word can be of any length that an English word can be.

Input

Input consists of several test cases. The first line of each case contains a single positive integer n. Several lines of text follow which will contain no more than 10000 words. The text for each case is terminated by a single line containing EndOfText. EndOfText does not appear elsewhere in the input and is not considered a word.

Output

For each test case, output the words which occur n times in the input text, one word per line, lower case, in alphabetical order. If there are no such words in input, output the following line:There is no such word.Leave a blank line between cases.

Sample Input

2In practice, the difference between theory and practice is alwaysgreater than the difference between theory and practice in theory.	- AnonymousMan will occasionally stumble over the truth, but most of thetime he will pick himself up and continue on.        - W. S. L. ChurchillEndOfTextSample Output
betweendifferenceinwill
题目大意：给你一个文本，让你找出出现次数为n的字符串，每个测试数据之间输出一个空行，跟描述基本没有什么关系。
#include <cstdio>#include <iostream>#include <cstring>#include <sstream>#include <map>using namespace std;map<string,int>a;int main(){    string s,buf;    int n,flag=0;    while (~scanf("%d",&n))    {        if (flag)            puts("");        flag++;        a.clear();        while (getline(cin,s)&&s!="EndOfText")        {            for(int i=0; i<s.length(); i++)                if (isalpha(s[i]))                    s[i]=tolower(s[i]);                else                    s[i]=' ';            stringstream ss(s);//定义了一个字符串流，并用一个字符串初始化            while (ss>>buf)//将字符串流中的字符串一个个的输出到buf中            {                a[buf]++;                //cout<<buf<<endl;            }        }        int tt=0;        map<string,int>::iterator it;        for(it=a.begin(); it!=a.end(); it++)            if(it->second==n)            {                tt=1;                cout<<it->first<<endl;            }        if(!tt) printf("There is no such word./n");    }}