## 1227. Airplane Seat Assignment Probability

`n`

passengers board an airplane with exactly `n`

seats. The first passenger has lost the ticket and picks a seat randomly. But after that, the rest of passengers will:

- Take their own seat if it is still available,
- Pick other seats randomly when they find their seat occupied

What is the probability that the n-th person can get his own seat?

**Example 1:**

Input:n = 1Output:1.00000Explanation:The first person can only get the first seat.

**Example 2:**

Input:n = 2Output:0.50000Explanation:The second person has a probability of 0.5 to get the second seat (when first person gets the first seat).

**Constraints:**

`1 <= n <= 10^5`

## Rust Solution

```
struct Solution;
impl Solution {
fn nth_person_gets_nth_seat(n: i32) -> f64 {
if n > 1 {
0.5
} else {
1.0
}
}
}
#[test]
fn test() {
use assert_approx_eq::assert_approx_eq;
let n = 1;
let res = 1.0;
assert_approx_eq!(Solution::nth_person_gets_nth_seat(n), res);
let n = 2;
let res = 0.5;
assert_approx_eq!(Solution::nth_person_gets_nth_seat(n), res);
}
```

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