2144-MinimumCostOfBuyingCandiesWithDiscount.go

package main

// 2144. Minimum Cost of Buying Candies With Discount
// A shop is selling candies at a discount. 
// For every two candies sold, the shop gives a third candy for free.

// The customer can choose any candy to take away for free as long as the cost of the chosen candy is less than 
// or equal to the minimum cost of the two candies bought.
//     For example, if there are 4 candies with costs 1, 2, 3, and 4, 
//     and the customer buys candies with costs 2 and 3, 
//     they can take the candy with cost 1 for free, but not the candy with cost 4.

// Given a 0-indexed integer array cost, where cost[i] denotes the cost of the ith candy, 
// return the minimum cost of buying all the candies.

// Example 1:
// Input: cost = [1,2,3]
// Output: 5
// Explanation: We buy the candies with costs 2 and 3, and take the candy with cost 1 for free.
// The total cost of buying all candies is 2 + 3 = 5. This is the only way we can buy the candies.
// Note that we cannot buy candies with costs 1 and 3, and then take the candy with cost 2 for free.
// The cost of the free candy has to be less than or equal to the minimum cost of the purchased candies.

// Example 2:
// Input: cost = [6,5,7,9,2,2]
// Output: 23
// Explanation: The way in which we can get the minimum cost is described below:
// - Buy candies with costs 9 and 7
// - Take the candy with cost 6 for free
// - We buy candies with costs 5 and 2
// - Take the last remaining candy with cost 2 for free
// Hence, the minimum cost to buy all candies is 9 + 7 + 5 + 2 = 23.

// Example 3:
// Input: cost = [5,5]
// Output: 10
// Explanation: Since there are only 2 candies, we buy both of them. There is not a third candy we can take for free.
// Hence, the minimum cost to buy all candies is 5 + 5 = 10.

// Constraints:
//     1 <= cost.length <= 100
//     1 <= cost[i] <= 100

import "fmt"
import "sort"

func minimumCost(cost []int) int {
    sort.Ints(cost)
    res, sum := 0, 0
    for i := len(cost) - 1; i >= 0; i-- {
         if sum == 2 {
             sum = 0
         } else { 
             res +=cost[i]
             sum++
         }
    }
    return res
}

func minimumCost1(cost []int) int {
    sort.Ints(cost)
    res, rest := 0, len(cost) % 3
    for i := 0 ; i < rest ; i ++ {
        res += cost[i]
    }
    for i := len(cost) - 1 ; i >= rest ; i -= 3 {
        res += cost[i]
        res += cost[i - 1]
    }
    return res
}

func main() {
    // Example 1:
    // Input: cost = [1,2,3]
    // Output: 5
    // Explanation: We buy the candies with costs 2 and 3, and take the candy with cost 1 for free.
    // The total cost of buying all candies is 2 + 3 = 5. This is the only way we can buy the candies.
    // Note that we cannot buy candies with costs 1 and 3, and then take the candy with cost 2 for free.
    // The cost of the free candy has to be less than or equal to the minimum cost of the purchased candies.
    fmt.Println(minimumCost([]int{1,2,3})) // 5
    // Example 2:
    // Input: cost = [6,5,7,9,2,2]
    // Output: 23
    // Explanation: The way in which we can get the minimum cost is described below:
    // - Buy candies with costs 9 and 7
    // - Take the candy with cost 6 for free
    // - We buy candies with costs 5 and 2
    // - Take the last remaining candy with cost 2 for free
    // Hence, the minimum cost to buy all candies is 9 + 7 + 5 + 2 = 23.
    fmt.Println(minimumCost([]int{6,5,7,9,2,2})) // 23
    // Example 3:
    // Input: cost = [5,5]
    // Output: 10
    // Explanation: Since there are only 2 candies, we buy both of them. There is not a third candy we can take for free.
    // Hence, the minimum cost to buy all candies is 5 + 5 = 10.
    fmt.Println(minimumCost([]int{5,5})) // 10

    fmt.Println(minimumCost1([]int{1,2,3})) // 5
    fmt.Println(minimumCost1([]int{6,5,7,9,2,2})) // 23
    fmt.Println(minimumCost1([]int{5,5})) // 10
}