1768. Merge Strings Alternately

#### QUESTION:

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.
``````

#### EXPLANATION:

easy的题目, 直接用一个flag进行for循环就行

#### SOLUTION:

``````class Solution {
func mergeAlternately(_ word1: String, _ word2: String) -> String {
var result:String = ""
var flag:Bool = false
var index:Int = 0
var arr1 = Array(word1)
var arr2 = Array(word2)
while index < arr1.count || index < arr2.count {
if flag {
result += index > arr2.count - 1 ? "" : String(arr2[index])
index += 1
} else {
result += index > arr1.count - 1 ? "" : String(arr1[index])
}
flag = !flag
}
return result
}
}
``````