1768. Merge Strings Alternately

#array #string

Given two strings merge the strings by adding letters in alternating order, starting with word1. If a string is longer than the other, append the additional letters onto the end of the merged string.

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Intuition

• Iterate and keep adding characters from the string alternatively

Approach

• Iterate and add character alternatively till we reach the end of the string word1​ or word2​

• Add the remaining character as it is

Complexity

• Time complexity : O(m+n)

  • where the m,n are the length of the string word1​ & word2​

• Space complexity : O(m+n)

  • we store the merged string

Code

public String mergeAlternately(String word1, String word2) {
	if(word1.length() == 1) return word1+word2;        

	StringBuilder mergedString = new StringBuilder();
	int i = 0, j = 0;
	for (; i < word1.length() && j < word2.length();) {
		mergedString.append(word1.charAt(i++));
		mergedString.append(word2.charAt(j++));
	}

	
	if(word1.length() > i) { 
		mergedString.append(word1.substring(j,word1.length()));
		return mergedString.toString();
	}
	if(word2.length() > j) { 
		mergedString.append(word2.substring(j,word2.length()));
		return mergedString.toString();
	}

	return mergedString.toString();
}