Min Cost Climbing Stairs
<p>You are given an integer array <code>cost</code> where <code>cost[i]</code> is the cost of <code>i<sup>th</sup></code> step on a staircase. Once you pay the cost, you can either climb one or two steps.</p>

<p>You can either start from the step with index <code>0</code>, or the step with index <code>1</code>.</p>

<p>Return <em>the minimum cost to reach the top of the floor</em>.</p>

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

<pre>
<strong>Input:</strong> cost = [10,<u>15</u>,20]
<strong>Output:</strong> 15
<strong>Explanation:</strong> You will start at index 1.
- Pay 15 and climb two steps to reach the top.
The total cost is 15.
</pre>

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

<pre>
<strong>Input:</strong> cost = [<u>1</u>,100,<u>1</u>,1,<u>1</u>,100,<u>1</u>,<u>1</u>,100,<u>1</u>]
<strong>Output:</strong> 6
<strong>Explanation:</strong> You will start at index 0.
- Pay 1 and climb two steps to reach index 2.
- Pay 1 and climb two steps to reach index 4.
- Pay 1 and climb two steps to reach index 6.
- Pay 1 and climb one step to reach index 7.
- Pay 1 and climb two steps to reach index 9.
- Pay 1 and climb one step to reach the top.
The total cost is 6.
</pre>

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

<ul>
	<li><code>2 &lt;= cost.length &lt;= 1000</code></li>
	<li><code>0 &lt;= cost[i] &lt;= 999</code></li>
</ul>
Array; Dynamic Programming
class Solution {
public:
    int minCostClimbingStairs(vector<int>& cost) {
        int n = cost.size();
        int f[n];
        memset(f, -1, sizeof(f));
        auto dfs = [&](this auto&& dfs, int i) -> int {
            if (i >= n) {
                return 0;
            }
            if (f[i] < 0) {
                f[i] = cost[i] + min(dfs(i + 1), dfs(i + 2));
            }
            return f[i];
        };
        return min(dfs(0), dfs(1));
    }
};
