分配重复整数

import java.util.HashMap;
import java.util.Map;
import java.util.Arrays;
import java.util.stream.Collectors;

/**
 * Solution for the given problem using Java Streams.
 * The approach is similar to the standard Java solution but uses streams for frequency calculation and sorting.
 */
public class SolutionStream {
    public boolean canDistribute(int[] nums, int[] quantity) {
        // Count the frequency of each number in nums
        Map<Integer, Long> freqMap = Arrays.stream(nums).boxed()
            .collect(Collectors.groupingBy(e -> e, Collectors.counting()));
        // Convert frequency map values to a list
        List<Long> freqList = new ArrayList<>(freqMap.values());
        // Sort quantity in descending order to try larger orders first
        Arrays.sort(quantity);
        reverse(quantity);
        return backtrack(freqList, quantity, 0);
    }

    private void reverse(int[] quantity) {
        int left = 0, right = quantity.length - 1;
        while (left < right) {
            int temp = quantity[left];
            quantity[left] = quantity[right];
            quantity[right] = temp;
            left++;
            right--;
        }
    }

    private boolean backtrack(List<Long> freqList, int[] quantity, int idx) {
        if (idx == quantity.length) {
            return true;
        }
        for (int i = 0; i < freqList.size(); i++) {
            if (freqList.get(i) >= quantity[idx]) {
                freqList.set(i, freqList.get(i) - quantity[idx]);
                if (backtrack(freqList, quantity, idx + 1)) {
                    return true;
                }
                freqList.set(i, freqList.get(i) + quantity[idx]);
            }
        }
        return false;
    }
}