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Ruairí O'Brien
Ruairí O'Brien

Posted on • Edited on

Day 8 - Check If Two String Arrays are Equivalent

#leetcode #python

The Problem

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.
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Example 2:

Input: word1 = ["a", "cb"], word2 = ["ab", "c"] Output: false
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Example 3:

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

  • 1 <= word1.length, word2.length <= 10^3
  • 1 <= word1[i].length, word2[i].length <= 10^3
  • 1 <= sum(word1[i].length), sum(word2[i].length) <= 10^3
  • word1[i] and word2[i] consist of lowercase letters.

My Tests

Link to code

import pytest from .Day8 import Solution s = Solution() @pytest.mark.parametrize( "word1,word2,expected", [ (["ab", "c"], ["a", "bc"], True), (["a", "cb"], ["ab", "c"], False), (["abc", "d", "defg"], ["abcddefg"], True), ], ) def test_array_strings_are_equal(word1, word2, expected): assert s.arrayStringsAreEqual(word1, word2) == expected
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My Solution 

from typing import List class Solution: def arrayStringsAreEqual(self, word1: List[str], word2: List[str]) -> bool: return "".join(map(str, word1)) == "".join(map(str, word2))
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Analysis

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My Commentary

Not much to say about this one really. It's running in O(n). Not sure how to squeeze much more out of it.

We convert each list to a single string and compare them.

Top comments (2)

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mhmelshaaer profile image
Mouhammed Elshaaer • • Edited

You can optimize for memory and a much better time complexity for best-case scenarios.

bool arrayStringsAreEqual(vector<string>& word1, vector<string>& word2) { int w1Index=0, i=0, w1N = word1.size(), w2Index=0, j=0, w2N = word2.size(); while(w1Index < w1N && w2Index < w2N) { if (word1[w1Index][i] != word2[w2Index][j]) return false; if(word1[w1Index].length() - 1 > i) ++i; else { ++w1Index; i = 0; } if(word2[w2Index].length() - 1 > j) ++j; else { ++w2Index; j = 0; } } return w1Index + w2Index == w1N + w2N; }
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ruarfff profile image
Ruairí O'Brien •

That's cool. Thank you!

I did a python version of it to test it out:

def arrayStringsAreEqual(self, word1: List[str], word2: List[str]) -> bool: w1, i, w1n = 0, 0, len(word1) w2, j, w2n = 0, 0, len(word2) while w1 < w1n and w2 < w2n: if word1[w1][i] != word2[w2][j]: return False if len(word1[w1]) - 1 > i: i += 1 else: w1 += 1 i = 0 if len(word2[w2]) - 1 > j: j += 1 else: w2 += 1 j = 0 return w1 + w2 == w1n + w2n
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