LeetCode: Check If Two String Arrays are Equivalent

 The problem statement is copy pasted from leetcode as it is:

Given two string arrays word1 and word2, return true if the two arrays represent the same string, and false otherwise.

A string is represented by an array if the array elements concatenated in order forms the string.

 

Example 1:

Input: word1 = ["ab", "c"], word2 = ["a", "bc"]
Output: true
Explanation:
word1 represents string "ab" + "c" -> "abc"
word2 represents string "a" + "bc" -> "abc"
The strings are the same, so return true.

Example 2:

Input: word1 = ["a", "cb"], word2 = ["ab", "c"]
Output: false

Example 3:

Input: word1  = ["abc", "d", "defg"], word2 = ["abcddefg"]
Output: true

 

Constraints:

• 1 <= word1.length, word2.length <= 103
• 1 <= word1[i].length, word2[i].length <= 103
• 1 <= sum(word1[i].length), sum(word2[i].length) <= 103
• word1[i] and word2[i] consist of lowercase letters.

My Solution:

package madwani.sushil.leetcode.Jan_8_15_2021;

public class CheckIfTwoStringArraysAreEquivalent {
    public static void main(String[] args) {
        String[] word1 = new String[] {};
        String[] word2 = new String[] {};
        System.out.println(arrayStringsAreEqual(word1, word2));
    }

    public static boolean arrayStringsAreEqual(String[] word1, String[] word2) {
        StringBuilder string1 = new StringBuilder();
        StringBuilder string2 = new StringBuilder();
        int i = 0, j =0;
        while (i < word1.length || j < word2.length) {
            if (i < word1.length) {
                string1.append(word1[i++]);
            }
            if (j < word2.length) {
                string2.append(word2[j++]);
            }
        }
        return string1.toString().equals(string2.toString()) ;
    }
}

// time complexity : O(N)
// space complexity: O(1)
public static boolean arrayStringsAreEqual1(String[] word1, String[] word2) {
    int k=0, m=0;
    for (int i=0, j=0; i< word1.length && j < word2.length;) {
        while (k< word1[i].length() && m < word2[j].length()) {
            if (word1[i].charAt(k) != word2[j].charAt(m)) {
                return false;
            }
            k++; m++;
        }
        if ( k == word1[i].length()) {
            k = 0; i++;
        }
        if ( m == word2[j].length()) {
            m = 0; j++;
        }
    }
    if ( k !=0 || m !=0) {
        return false;
    }
    return true;
}