681. Next Closest Time

Given a `time` represented in the format `"HH:MM"`, form the next closest time by reusing the current digits. There is no limit on how many times a digit can be reused.

You may assume the given input string is always valid. For example, `"01:34"`, `"12:09"` are all valid. `"1:34"`, `"12:9"` are all invalid.

Example 1:

```Input: time = "19:34"
Output: "19:39"
Explanation: The next closest time choosing from digits 1, 9, 3, 4, is 19:39, which occurs 5 minutes later.
It is not 19:33, because this occurs 23 hours and 59 minutes later.
```

Example 2:

```Input: time = "23:59"
Output: "22:22"
Explanation: The next closest time choosing from digits 2, 3, 5, 9, is 22:22.
It may be assumed that the returned time is next day's time since it is smaller than the input time numerically.
```

Constraints:

• `time.length == 5`
• `time` is a valid time in the form `"HH:MM"`.
• `0 <= HH < 24`
• `0 <= MM < 60`

681. Next Closest Time
``````struct Solution;

impl Solution {
fn next_closest_time(time: String) -> String {
let h = time[..2].parse::<usize>().unwrap();
let m = time[3..].parse::<usize>().unwrap();
let a = h / 10;
let b = h % 10;
let c = m / 10;
let d = m % 10;
let set = 1 << a | 1 << b | 1 << c | 1 << d;
let mut found = false;
for _ in 0..2 {
for i in 0..24 {
for j in 0..60 {
if !found {
if i == h && j == m {
found = true;
}
} else {
let a = i / 10;
let b = i % 10;
let c = j / 10;
let d = j % 10;
let next_set = 1 << a | 1 << b | 1 << c | 1 << d;
if (next_set | set) == set {
return format!("{}{}:{}{}", a, b, c, d);
}
}
}
}
}
"".to_string()
}
}

#[test]
fn test() {
let time = "19:34".to_string();
let res = "19:39".to_string();
assert_eq!(Solution::next_closest_time(time), res);
let time = "23:59".to_string();
let res = "22:22".to_string();
assert_eq!(Solution::next_closest_time(time), res);
}
``````