Reverse the order of the words
A text filter turns a sentence back to front, word by word, without disturbing the words themselves.
- Only the order of the words changes; the letters inside each word stay put.
- Runs of whitespace collapse to one space, and the ends are trimmed.
- Text with no words gives an empty string.
reverseWords(text: string) → string
C++ needs a compiler and Drill does not host one yet, so this page is the reference rather than an exercise: the problem, worked examples, and the solution in full. To type it out, the same problem runs in Python.
Where you start
std::string reverseWords(std::string text) {
}Worked examples
| Call | Result |
|---|---|
reverseWords(std::string("the quick brown fox")) | std::string("fox brown quick the") |
reverseWords(std::string(" a b ")) | std::string("b a") |
reverseWords(std::string("one")) | std::string("one") |
reverseWords(std::string("")) | std::string("") |
Hint
Split on whitespace, reverse the list, join with a single space.
Reference solution in C++
std::string reverseWords(std::string text) {
istringstream in(text);
std::vector<string> words;
string w;
while (in >> w) words.push_back(w);
string result;
for (size_t i = words.size(); i > 0; i--) {
if (!result.empty()) result += ' ';
result += words[i - 1];
}
return result;
}