Minimum Consecutive Cards to Pick Up
<p>You are given an integer array <code>cards</code> where <code>cards[i]</code> represents the <strong>value</strong> of the <code>i<sup>th</sup></code> card. A pair of cards are <strong>matching</strong> if the cards have the <strong>same</strong> value.</p>

<p>Return<em> the <strong>minimum</strong> number of <strong>consecutive</strong> cards you have to pick up to have a pair of <strong>matching</strong> cards among the picked cards.</em> If it is impossible to have matching cards, return <code>-1</code>.</p>

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

<pre>
<strong>Input:</strong> cards = [3,4,2,3,4,7]
<strong>Output:</strong> 4
<strong>Explanation:</strong> We can pick up the cards [3,4,2,3] which contain a matching pair of cards with value 3. Note that picking up the cards [4,2,3,4] is also optimal.
</pre>

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

<pre>
<strong>Input:</strong> cards = [1,0,5,3]
<strong>Output:</strong> -1
<strong>Explanation:</strong> There is no way to pick up a set of consecutive cards that contain a pair of matching cards.
</pre>

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

<ul>
	<li><code>1 &lt;= cards.length &lt;= 10<sup>5</sup></code></li>
	<li><code>0 &lt;= cards[i] &lt;= 10<sup>6</sup></code></li>
</ul>
Array; Hash Table; Sliding Window
func minimumCardPickup(cards []int) int {
	last := map[int]int{}
	n := len(cards)
	ans := n + 1
	for i, x := range cards {
		if j, ok := last[x]; ok && ans > i-j+1 {
			ans = i - j + 1
		}
		last[x] = i
	}
	if ans > n {
		return -1
	}
	return ans
}