1859. Sorting the Sentence

Description

A sentence is a list of words that are separated by a single space with no leading or trailing spaces. Each word consists of lowercase and uppercase English letters.

A sentence can be shuffled by appending the 1-indexed word position to each word then rearranging the words in the sentence.

  • For example, the sentence "This is a sentence" can be shuffled as "sentence4 a3 is2 This1" or "is2 sentence4 This1 a3".

Given a shuffled sentence s containing no more than 9 words, reconstruct and return the original sentence.

 

Example 1:

Input: s = "is2 sentence4 This1 a3"
Output: "This is a sentence"
Explanation: Sort the words in s to their original positions "This1 is2 a3 sentence4", then remove the numbers.

Example 2:

Input: s = "Myself2 Me1 I4 and3"
Output: "Me Myself and I"
Explanation: Sort the words in s to their original positions "Me1 Myself2 and3 I4", then remove the numbers.

 

Constraints:

  • 2 <= s.length <= 200
  • s consists of lowercase and uppercase English letters, spaces, and digits from 1 to 9.
  • The number of words in s is between 1 and 9.
  • The words in s are separated by a single space.
  • s contains no leading or trailing spaces.

Solutions

Solution 1: String Splitting

First, we split the string $s$ by spaces to get the string array $words$. Then, we create a string array $ans$ of length $|words|$ to store the answer.

Next, we iterate over each string $w$ in the string array $words$, find the position $i$ represented by the last character of $w$, then take the first $|w|-1$ characters of $w$ as the new string $w’$, and place $w’$ in the $i$th position of the array $ans$.

Finally, we join the array $ans$ into a string by spaces, which is the answer.

The time complexity is $O(n)$, and the space complexity is $O(n)$. Where $n$ is the length of the string $s$.

Python Code
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class Solution:
    def sortSentence(self, s: str) -> str:
        ws = [(w[:-1], int(w[-1])) for w in s.split()]
        ws.sort(key=lambda x: x[1])
        return ' '.join(w for w, _ in ws)

Java Code
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class Solution {
    public String sortSentence(String s) {
        String[] ws = s.split(" ");
        int n = ws.length;
        String[] ans = new String[n];
        for (int i = 0; i < n; ++i) {
            String w = ws[i];
            ans[w.charAt(w.length() - 1) - '1'] = w.substring(0, w.length() - 1);
        }
        return String.join(" ", ans);
    }
}

C++ Code
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class Solution {
public:
    string sortSentence(string s) {
        istringstream iss(s);
        string w;
        vector<string> ws;
        while (iss >> w) {
            ws.push_back(w);
        }
        vector<string> ss(ws.size());
        for (auto& w : ws) {
            ss[w.back() - '1'] = w.substr(0, w.size() - 1);
        }
        string ans;
        for (auto& w : ss) {
            ans += w + " ";
        }
        ans.pop_back();
        return ans;
    }
};

Go Code
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func sortSentence(s string) string {
	ws := strings.Split(s, " ")
	ans := make([]string, len(ws))
	for _, w := range ws {
		ans[w[len(w)-1]-'1'] = w[:len(w)-1]
	}
	return strings.Join(ans, " ")
}

TypeScript Code
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function sortSentence(s: string): string {
    const ws = s.split(' ');
    const ans = Array(ws.length);
    for (const w of ws) {
        ans[w.charCodeAt(w.length - 1) - '1'.charCodeAt(0)] = w.slice(0, -1);
    }
    return ans.join(' ');
}

JavaScript Code
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/**
 * @param {string} s
 * @return {string}
 */
var sortSentence = function (s) {
    const ws = s.split(' ');
    const ans = Array(ws.length);
    for (const w of ws) {
        ans[w.charCodeAt(w.length - 1) - '1'.charCodeAt(0)] = w.slice(0, -1);
    }
    return ans.join(' ');
};

Solution 2

Python Code
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class Solution:
    def sortSentence(self, s: str) -> str:
        ws = s.split()
        ans = [None] * len(ws)
        for w in ws:
            ans[int(w[-1]) - 1] = w[:-1]
        return ' '.join(ans)