You are given an integer array `cost`

where `cost[i]`

is the cost of `i`

step on a staircase. Once you pay the cost, you can either climb one or two steps.^{th}

You can either start from the step with index `0`

, or the step with index `1`

.

Return *the minimum cost to reach the top of the floor*.

**Example 1:**

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

**Example 2:**

Input:cost = [1,100,1,1,1,100,1,1,100,1]Output:6Explanation: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.

**Constraints:**

`2 <= cost.length <= 1000`

`0 <= cost[i] <= 999`

` ````
```class Solution {
public:
int minCostClimbingStairs(vector& cost) {
int n=cost.size();
for(int i=n-3; i>=0; i--)
{
cost[i]+=min(cost[i+1],cost[i+2]);
}
return min(cost[0],cost[1]);
}
};

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