2124. Check if All A's Appears Before All B's

#### QUESTION:

Given a string s consisting of only the characters ‘a’ and ‘b’, return true if every ‘a’ appears before every ‘b’ in the string. Otherwise, return false.

Example 1:

``````Input: s = "aaabbb"
Output: true
Explanation:
The 'a's are at indices 0, 1, and 2, while the 'b's are at indices 3, 4, and 5.
Hence, every 'a' appears before every 'b' and we return true.
``````

Example 2:

``````Input: s = "abab"
Output: false
Explanation:
There is an 'a' at index 2 and a 'b' at index 1.
Hence, not every 'a' appears before every 'b' and we return false.
``````

Example 3:

``````Input: s = "bbb"
Output: true
Explanation:
There are no 'a's, hence, every 'a' appears before every 'b' and we return true.
``````

Constraints:

``````1 <= s.length <= 100
s[i] is either 'a' or 'b'.
``````

#### EXPLANATION:

easy的题目, 一个for循环就行.

#### SOLUTION:

``````class Solution {
func checkString(_ s: String) -> Bool {
var result:Bool = true
var arr:[Character] = Array(s)
for index in stride(from: 1, to: s.count, by: 1) {
if arr[index].asciiValue! < arr[index-1].asciiValue! {
return false
}
}
return result
}
}
``````
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