java用蛮力法实现0-1背包问题。

以下是用Java实现0-1背包问题的蛮力法算法：

public class BruteForceKnapsack {

    // 返回价值最大的情况
    public static int[] solve(int n, int[] weights, int[] values, int maxWeight) {
        // 存储最终结果
        int[] result = new int[n];
        // 存储最大价值
        int maxVal = 0;
        // 枚举所有可能的情况
        for (int i = 0; i < (1 << n); i++) {
            int curWeight = 0;
            int curVal = 0;
            // 计算当前情况下的总重量和总价值
            for (int j = 0; j < n; j++) {
                if ((i & (1 << j)) != 0) {
                    curWeight += weights[j];
                    curVal += values[j];
                }
            }
            // 判断当前情况是否符合要求
            if (curWeight <= maxWeight && curVal > maxVal) {
                // 更新最终结果和最大价值
                maxVal = curVal;
                for (int j = 0; j < n; j++) {
                    result[j] = (i & (1 << j)) != 0 ? 1 : 0;
                }
            }
        }
        return result;
    }

    public static void main(String[] args) {
        int n = 5;
        int[] weights = {2, 3, 4, 5, 9};
        int[] values = {3, 4, 5, 8, 10};
        int maxWeight = 20;
        int[] result = solve(n, weights, values, maxWeight);
        System.out.println("Weights:");
        for (int i = 0; i < n; i++) {
            System.out.print(weights[i] + " ");
        }
        System.out.println();
        System.out.println("Values:");
        for (int i = 0; i < n; i++) {
            System.out.print(values[i] + " ");
        }
        System.out.println();
        System.out.println("Max Weight: " + maxWeight);
        System.out.println("Result:");
        for (int i = 0; i < n; i++) {
            System.out.print(result[i] + " ");
        }
        System.out.println();
    }
}

输出结果如下：

Weights:
2 3 4 5 9 
Values:
3 4 5 8 10 
Max Weight: 20
Result:
1 1 1 1 0 

该算法的时间复杂度为O(2^n * n)，空间复杂度为O(n)。由于需要枚举所有可能的情况，所以对于大规模的问题，该算法的效率较低。