A password is considered strong if the below conditions are all met:

• It has at least `6` characters and at most `20` characters.
• It contains at least one lowercase letter, at least one uppercase letter, and at least one digit.
• It does not contain three repeating characters in a row (i.e., `"...aaa..."` is weak, but `"...aa...a..."` is strong, assuming other conditions are met).

Given a string `password`, return the minimum number of steps required to make `password` strong. if `password` is already strong, return `0`.

In one step, you can:

• Insert one character to `password`,
• Delete one character from `password`, or
• Replace one character of `password` with another character.

Example 1:

```Input: password = "a"
Output: 5
```

Example 2:

```Input: password = "aA1"
Output: 3
```

Example 3:

```Input: password = "1337C0d3"
Output: 0
```

Constraints:

• `1 <= password.length <= 50`
• `password` consists of letters, digits, dot `'.'` or exclamation mark `'!'`.

## Rust Solution

``````struct Solution;

impl Solution {
fn strong_password_checker(s: String) -> i32 {
let mut missing = 3;
let s: Vec<char> = s.chars().collect();
if s.iter().any(|c| c.is_lowercase()) {
missing -= 1;
}
if s.iter().any(|c| c.is_uppercase()) {
missing -= 1;
}
if s.iter().any(|c| c.is_digit(10)) {
missing -= 1;
}
let mut replace = 0;
let mut one = 0;
let mut two = 0;
let mut three = 0;
let mut i = 2;
while i < s.len() {
if s[i] == s[i - 1] && s[i] == s[i - 2] {
let mut length = 2;
while i < s.len() && s[i] == s[i - 1] {
length += 1;
i += 1;
}
replace += length / 3;
if length % 3 == 0 {
one += 1;
} else if length % 3 == 1 {
two += 1;
} else {
three += 1;
}
} else {
i += 1;
}
}
if s.len() < 6 {
return missing.max(6 - s.len()) as i32;
}
if s.len() <= 20 {
return missing.max(replace) as i32;
}

let delete = s.len() - 20;
let delete_one = one.min(delete);
let delete_one_left = delete - delete_one;
let delete_two = (two * 2).min(delete_one_left);
let delete_two_left = delete_one_left - delete_two;
let delete_three = ((one + two + three) * 3).min(delete_two_left);
replace -= delete_one + delete_two / 2 + delete_three / 3;
(delete + missing.max(replace)) as i32
}
}

#[test]
fn test() {
let s = "aaa111".to_string();
let res = 2;