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Formatted question description: https://leetcode.ca/all/1816.html

1816. Truncate Sentence

Level

Easy

Description

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

  • For example, "Hello World", "HELLO", and "hello world hello world" are all sentences.

You are given a sentence s and an integer k. You want to truncate s such that it contains only the first k words. Return s after truncating it.

Example 1:

Input: s = “Hello how are you Contestant”, k = 4

Output: “Hello how are you”

Explanation:

The words in s are [“Hello”, “how” “are”, “you”, “Contestant”].

The first 4 words are [“Hello”, “how”, “are”, “you”].

Hence, you should return “Hello how are you”.

Example 2:

Input: s = “What is the solution to this problem”, k = 4

Output: “What is the solution”

Explanation:

The words in s are [“What”, “is” “the”, “solution”, “to”, “this”, “problem”].

The first 4 words are [“What”, “is”, “the”, “solution”].

Hence, you should return “What is the solution”.

Example 3:

Input: s = “chopper is not a tanuki”, k = 5

Output: “chopper is not a tanuki”

Constraints:

  • 1 <= s.length <= 500
  • k is in the range [1, the number of words in s].
  • s consist of only lowercase and uppercase English letters and spaces.
  • The words in s are separated by a single space.
  • There are no leading or trailing spaces.

Solution

Split s into an array using spaces. Then generate the truncated sentence by concatenating the first k elements of the array, and return the truncated sentence.

  • class Solution {
    public String truncateSentence(String s, int k) {
        String[] array = s.split(" ");
        StringBuffer sb = new StringBuffer(array[0]);
        for (int i = 1; i < k; i++)
            sb.append(" " + array[i]);
        return sb.toString();
    }
}

############

class Solution {
    public String truncateSentence(String s, int k) {
        for (int i = 0; i < s.length(); ++i) {
            if (s.charAt(i) == ' ' && (--k) == 0) {
                return s.substring(0, i);
            }
        }
        return s;
    }
}

  • // OJ: https://leetcode.com/problems/truncate-sentence/
// Time: O(N)
// Space: O(N)
class Solution {
public:
    string truncateSentence(string s, int k) {
        istringstream ss(s);
        string word, ans;
        int i = 0;
        while (ss >> word && i < k) {
            ans += (i > 0 ? " " : "") + word;
            ++i;
        }
        return ans;
    }
};

  • class Solution:
    def truncateSentence(self, s: str, k: int) -> str:
        for i, c in enumerate(s):
            k -= c == ' '
            if k == 0:
                return s[:i]
        return s

############

# 1816. Truncate Sentence
# https://leetcode.com/problems/truncate-sentence

class Solution:
    def truncateSentence(self, s: str, k: int) -> str:
        return " ".join(s.split()[:k])


  • func truncateSentence(s string, k int) string {
	for i, c := range s {
		if c == ' ' {
			k--
		}
		if k == 0 {
			return s[:i]
		}
	}
	return s
}

  • /**
 * @param {string} s
 * @param {number} k
 * @return {string}
 */
var truncateSentence = function (s, k) {
    for (let i = 0; i < s.length; ++i) {
        if (s[i] == ' ' && --k == 0) {
            return s.slice(0, i);
        }
    }
    return s;
};


  • function truncateSentence(s: string, k: number): string {
    for (let i = 0; i < s.length; ++i) {
        if (s[i] === ' ' && --k === 0) {
            return s.slice(0, i);
        }
    }
    return s;
}

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