paa/cutting_rod.cpp at master · r0drigopaes/paa · GitHub

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/**
Programação Dinâmica
Problema Cutting Rod
Rodrigo Paes
*/

#include <bits/stdc++.h>
using namespace std;

#define MAX 10001

int values[MAX];
int memo[MAX];

int naive(int n)
{
	if (n == 0)
	{
		return 0;
	}
	else
	{
		int best = INT_MIN;
		for (int i = 0; i < n; ++i)
		{
			best = max(best, values[i] + naive(n-i-1));
		}
		return best;
	}
}

int topdown_dp(int n)
{
	if (memo[n] != -1)
	{
		return memo[n];
	}
	if (n == 0)
	{
		memo[n] = 0;
	}
	else
	{
		int best = INT_MIN;
		for (int i = 0; i < n; ++i)
		{
			best = max(best, values[i] + topdown_dp(n-i-1));
		}
		memo[n]	= best;
	}
	return memo[n];
}

int bottomup_dp(int n)
{
	int best;
	memo[0] = 0;

	// j é o tamanho do subproblema
	for (int j = 1; j <= n; ++j)
	{
		best = INT_MIN;
		for (int i=0; i < j; ++i)
		{
			best = max(best, values[i] + memo[j-i-1]);
		}
		memo[j] = best;
	}
	return memo[n];
}

int main()
{
	int n;
	scanf("%d", &n);
	while (n)
	{
		for (int i=0; i < n; ++i)
		{
			scanf("%d", &values[i]);
		}
		memset( memo, -1, sizeof memo);
		// printf("%d\n", topdown_dp(n));
		// printf("%d\n", bottomup_dp(n));
		// printf("%d\n", naive(n));
		scanf("%d", &n);
	}
	return 0;
}