recursion problem(IsMeasurable)(Is this correct?)

最新推荐文章于 2024-02-26 19:15:12 发布

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最新推荐文章于 2024-02-26 19:15:12 发布

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本文介绍了一种递归算法来判断是否能通过给定的一组物品重量组合达到目标重量。通过对物品进行递归分解，算法考虑了每个物品可能被加入、排除或作为负重的情况。该算法适用于解决物品组合称重问题。

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#include <iostream>
#include <iomanip>
#include <string>

using namespace std;

bool IsMeasurable(int target, int weights[], int nWeights);
void SwapArray(int weights[], int i, int j);

int main()
{
	int sampleWeights[] = { 1, 3 };
	int nSampleWeights = 2;

	cout << boolalpha;
	cout << IsMeasurable(2, sampleWeights, nSampleWeights) << endl;
	cout << IsMeasurable(5, sampleWeights, nSampleWeights) << endl;

	return 0;
}

bool IsMeasurable(int target, int weights[], int nWeights)
{
	// simple case
	if (target == 0 && nWeights == 0) {
		return true;
	}
	if ((target == 0 && nWeights != 0) ||
		(target != 0 && nWeights == 0)) {
		return false;
	}

	// recursive decomposition
	for (int i = 0; i < nWeights; i++) {
		int weight = weights[i];
		SwapArray(weights, i, nWeights-1);
		if (IsMeasurable(target-weight, weights, nWeights-1) ||
			IsMeasurable(target, weights, nWeights-1) ||
			IsMeasurable(target + weight, weights,nWeights-1)) {
				return true;
		}
		SwapArray(weights, i, nWeights-1);
	}
	return false;
}

void SwapArray(int weights[], int i, int j) {
	int temp = weights[i];
	weights[i] = weights[j];
	weights[j] = temp;
}