Separate the Digits in an Array
<p>Given an array of positive integers <code>nums</code>, return <em>an array </em><code>answer</code><em> that consists of the digits of each integer in </em><code>nums</code><em> after separating them in <strong>the same order</strong> they appear in </em><code>nums</code>.</p>

<p>To separate the digits of an integer is to get all the digits it has in the same order.</p>

<ul>
	<li>For example, for the integer <code>10921</code>, the separation of its digits is <code>[1,0,9,2,1]</code>.</li>
</ul>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> nums = [13,25,83,77]
<strong>Output:</strong> [1,3,2,5,8,3,7,7]
<strong>Explanation:</strong> 
- The separation of 13 is [1,3].
- The separation of 25 is [2,5].
- The separation of 83 is [8,3].
- The separation of 77 is [7,7].
answer = [1,3,2,5,8,3,7,7]. Note that answer contains the separations in the same order.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> nums = [7,1,3,9]
<strong>Output:</strong> [7,1,3,9]
<strong>Explanation:</strong> The separation of each integer in nums is itself.
answer = [7,1,3,9].
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
	<li><code>1 &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
</ul>
Array; Simulation
impl Solution {
    pub fn separate_digits(nums: Vec<i32>) -> Vec<i32> {
        let mut ans = Vec::new();
        for &num in nums.iter() {
            let mut num = num;
            let mut t = Vec::new();
            while num != 0 {
                t.push(num % 10);
                num /= 10;
            }
            t.into_iter().rev().for_each(|v| ans.push(v));
        }
        ans
    }
}
