这个怎么样（使用 STL、比较器和仿函数）？
注意：所有假设和解释都在源代码本身中。
#include <iostream>
#include <string>
#include <vector>
#include <cstdlib>
#include <sstream>
#include <algorithm>
#include <cctype>
#include <utility>
#include <string.h>
bool compare (const std::pair<int, int>& l, const std::pair<int, int>& r) {
return l.first < r.first;
}
//functor/unary predicate:
struct CompareFirst {
CompareFirst(int val) : val_(val) {}
bool operator()(const std::pair<int, int>& p) const {
return (val_ == p.first);
}
private:
int val_;
};
int main() {
char delims[] = ".,!?";
char noise[] ="-'";
//I'm assuming you've read the text from some file, and that information has been stored in a string. Or, the information is a string (like below):
std::string input = "This is fun-\nny, Mr.P and I've never seen\nthis ice-cream flavour\nbefore.Crazy eh?\n#\nThis is fun-\nny! Mr.P and I've never seen\nthis ice-cream flavour\nbefore.Crazy eh?\n#\n";
std::istringstream iss(input);
std::string temp;
//first split the string by #
while(std::getline(iss, temp, '#')) {
//find all the occurences of the hypens as it crosses lines, and remove the newline:
std::string::size_type begin = 0;
while(std::string::npos != (begin = temp.find('-', begin))) {
//look at the character in front of the current hypen and erase it if it's a newline, if it is - remove it
if (temp[begin+1] == '\n') {
temp.erase(begin+1, 1);
}
++begin;
}
//now, erase all the `noise` characters ("'-") as these count as these punctuation count as zero
for (int i = 0; i < strlen(noise); ++i) {
//this replaces all the hyphens and apostrophes with nothing
temp.erase(std::remove(temp.begin(), temp.end(), noise[i]), temp.end());//since hyphens occur across two lines, you need to erase newlines
}//at this point, everything is dandy for complete substitution
//now try to remove any other delim chracters by replacing them with spaces
for (int i = 0; i < strlen(delims); ++i) {
std::replace(temp.begin(), temp.end(), delims[i], ' ');
}
std::vector<std::pair<int, int> > occurences;
//initialize another input stringstream to make use of the whitespace
std::istringstream ss(temp);
//now use the whitespace to tokenize
while (ss >> temp) {
//try to find the token's size in the occurences
std::vector<std::pair<int, int> >::iterator it = std::find_if(occurences.begin(), occurences.end(), CompareFirst(temp.size()));
//if found, increment count by 1
if (it != occurences.end()) {
it->second += 1;//increment the count
}
//this is the first time it has been created. Store value, and a count of 1
else {
occurences.push_back(std::make_pair<int, int>(temp.size(), 1));
}
}
//now sort and output:
std::stable_sort(occurences.begin(), occurences.end(), compare);
for (int i = 0; i < occurences.size(); ++i) {
std::cout << occurences[i].first << " " << occurences[i].second << "\n";
}
std::cout << "\n";
}
return 0;
}
91 行，所有原版 C++98。
我所做的大致轮廓是：
- 由于连字符跨越两行，找到所有连字符并删除它们后面的所有换行符。
-
有些字符不会增加单词的长度，例如合法的连字符和撇号。 找到并删除它们，因为它使标记化更容易。
-
现在可以找到所有其他剩余的分隔符并将其替换为空格。为什么？因为我们可以通过使用流（其默认操作是跳过空格）来利用空格。
- 如前所述，创建一个流并通过空格标记文本。
-
存储标记的长度及其出现次数。
-
对token的长度进行排序，然后输出token的长度和对应的出现次数。
参考：
https://stackoverflow.com/a/5815875/866930
https://stackoverflow.com/a/12008126/866930