leetcode2124: Check if All A's Appears Before All B's
carloscn opened this issue · comments
Description
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'.
Analysis
pub fn check_string(s: &str) -> bool
{
if s.len() < 1 {
return false;
}
let s_vec:Vec<char> = s.chars().collect();
let mut a_flag = false;
for i in 0..s_vec.len() {
let e = s_vec[s_vec.len() - i - 1];
if e == 'a' {
a_flag = true;
} else if e == 'b' {
if a_flag == true {
return false;
}
} else {
return false;
}
}
return true;
}