leetcode 1768 - Merge Strings Alternately

https://leetcode.com/problems/merge-strings-alternately/

You are given two strings word1 and word2. 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.

Return the merged string.

Example 1:

Input: word1 = “abc”, word2 = “pqr”
Output: “apbqcr”
Explanation: The merged string will be merged as so:
word1: a b c
word2: p q r
merged: a p b q c r
Example 2:

Input: word1 = “ab”, word2 = “pqrs”
Output: “apbqrs”
Explanation: Notice that as word2 is longer, “rs” is appended to the end.
word1: a b
word2: p q r s
merged: a p b q r s
Example 3:

Input: word1 = “abcd”, word2 = “pq”
Output: “apbqcd”
Explanation: Notice that as word1 is longer, “cd” is appended to the end.
word1: a b c d
word2: p q
merged: a p b q c d

Constraints:

1 <= word1.length, word2.length <= 100
word1 and word2 consist of lowercase English letters.

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class Solution {
public:
string mergeAlternately(string word1, string word2) {
int i = 0, j = 0;

string ans;

while (i < word1.size() && j < word2.size()) {
if ((i+j) % 2 == 0)
ans.push_back(word1[i++]);
else
ans.push_back(word2[j++]);
}

if (i < word1.size())
ans += word1.substr(i);
if (j < word2.size())
ans += word2.substr(j);

return ans;
}
};