Minimum Cost to Buy Oranges Problem Statement

You are given a bag of capacity 'W' kg and a list 'cost' of costs for packets of oranges with different weights. Each element at the i-th position in the list indicates the price of a packet weighing (i+1) kg.

If an element at i-th position in 'cost' is -1, it means the (i+1) kg packet is unavailable.

Your task is to determine the minimum total cost to purchase exactly 'W' kg of oranges. If it is not possible to buy exactly W kg, return -1. Assume an infinite supply of any available packet type.

Example:

Input:

N = 5, W = 5
cost = [20, 10, 4, 50, -1]

Output:

14

Explanation:

Minimum cost to achieve 5 kg of oranges is using one 3 kg packet costing 4, and one 2 kg packet costing 10. Total = 4 + 10 = 14.

Constraints:

• 1 ≤ N ≤ 1000
• 1 ≤ W ≤ 1000
• -1 ≤ cost[i] ≤ 1000000
• Time Limit: 1 sec