knapsack.go

package dynamic

// Knapsack Problem
// https://www.geeksforgeeks.org/0-1-knapsack-problem-dp-10/
// https://en.wikipedia.org/wiki/Knapsack_problem
// time complexity: O(n*maxWeight)
// space complexity: O(n*maxWeight)

import (
	"math"
)

// Max function - possible duplicate
func Max(a, b int) int {
	return int(math.Max(float64(a), float64(b)))
}

// Knapsack solves knapsack problem
// return maxProfit
func Knapsack(maxWeight int, weights, values []int) int {
	n := len(weights)
	m := maxWeight
	// create dp data structure
	dp := make([][]int, n+1)
	for i := range dp {
		dp[i] = make([]int, m+1)
	}
	for i := 0; i < len(weights); i++ {
		for j := 0; j <= maxWeight; j++ {
			if weights[i] > j {
				dp[i+1][j] = dp[i][j]
			} else {
				dp[i+1][j] = Max(dp[i][j-weights[i]]+values[i], dp[i][j])
			}
		}
	}
	return dp[n][m]
}

/*
func main() {
	maxWeight := 50
	values := []int{
		60, 100, 120,
	}
	weights := []int{
		10, 20, 30,
	}
	maxProfit := Knapsack(maxWeight, weights, values)
	fmt.Println(maxProfit)
}
*/