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Check If a Word Occurs As a Prefix of Any Word in a Sentence - MiniTV

Check If a Word Occurs As a Prefix of Any Word in a Sentence - मिनी टीवी

Given a sentence that consists of some words separated by a single space, and a searchWord.

You have to check if searchWord is a prefix of any word in sentence.

Return the index of the word in sentence where searchWord is a prefix of this word (1-indexed).

If searchWord is a prefix of more than one word, return the index of the first word (minimum index). If there is no such word return -1.

A prefix of a string S is any leading contiguous substring of S.

 

Example 1:

Input: sentence = "i love eating burger", searchWord = "burg"

Output: 4

Explanation: "burg" is prefix of "burger" which is the 4th word in the sentence.

 

Example 2:

Input: sentence = "this problem is an easy problem", searchWord = "pro"

Output: 2

Explanation: "pro" is prefix of "problem" which is the 2nd and the 6th word in the sentence, but we return 2 as it's the minimal index.

 

Example 3:

Input: sentence = "i am tired", searchWord = "you"

Output: -1

Explanation: "you" is not a prefix of any word in the sentence.

 

Example 4:

Input: sentence = "i use triple pillow", searchWord = "pill"

Output: 4

 

Example 5:

Input: sentence = "hello from the other side", searchWord = "they"

Output: -1

 

Constraints:

1 <= sentence.length <= 100

1 <= searchWord.length <= 10

sentence consists of lowercase English letters and spaces.

searchWord consists of lowercase English letters.

 

Solution:

using System;
using System.Collections.Generic;
using System.Text;

namespace LeetCode.AskGif.Easy.String
{
    public class IsPrefixOfWordSoln
    {
        public int IsPrefixOfWord(string sentence, string searchWord)
        {
            var word = 1;
            bool isBeginingOfWord = true;
            for(int i = 0; i < sentence.Length; i++)
            {
                if (isBeginingOfWord)
                {
                    isBeginingOfWord = false;
                    if (IsWordAPrefix(sentence, searchWord, i))
                    {
                        return word;
                    }
                    word++;
                }
                if(sentence[i] == ' ')
                {
                    isBeginingOfWord = true;
                }
            }
            return -1;
        }

        private bool IsWordAPrefix(string sentence, string searchWord, int i)
        {
            for(int j = 0; j < searchWord.Length; j++)
            {
                if(sentence[i+j] != searchWord[j])
                {
                    return false;
                }
            }

            return true;
        }
    }
}

 

Time Complexity: O(n)

Space Complexity: O(1)

 

Unit Tests:

using LeetCode.AskGif.Easy.String;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using System;
using System.Collections.Generic;
using System.Text;

namespace CodingUnitTest.Easy.String
{
    [TestClass]
    public class IsPrefixOfWordSolnTests
    {
        [TestMethod]
        public void IsPrefixOfWordSoln_First()
        {
            var sentence = "i love eating burger";
            var searchWord = "burg";
            var output = 4;
            var res = new IsPrefixOfWordSoln().IsPrefixOfWord(sentence, searchWord);

            Assert.AreEqual(res, output);
        }

        [TestMethod]
        public void IsPrefixOfWordSoln_Second()
        {
            var sentence = "this problem is an easy problem";
            var searchWord = "pro";
            var output = 2;
            var res = new IsPrefixOfWordSoln().IsPrefixOfWord(sentence, searchWord);

            Assert.AreEqual(res, output);
        }

        [TestMethod]
        public void IsPrefixOfWordSoln_Fourth()
        {
            var sentence = "i use triple pillow";
            var searchWord = "pill";
            var output = 4;
            var res = new IsPrefixOfWordSoln().IsPrefixOfWord(sentence, searchWord);

            Assert.AreEqual(res, output);
        }

        [TestMethod]
        public void IsPrefixOfWordSoln_Third()
        {
            var sentence = "i am tired";
            var searchWord = "you";
            var output = -1;
            var res = new IsPrefixOfWordSoln().IsPrefixOfWord(sentence, searchWord);

            Assert.AreEqual(res, output);
        }

        [TestMethod]
        public void IsPrefixOfWordSoln_Fifth()
        {
            var sentence = "hello from the other side";
            var searchWord = "they";
            var output = -1;
            var res = new IsPrefixOfWordSoln().IsPrefixOfWord(sentence, searchWord);

            Assert.AreEqual(res, output);
        }
    }
}