按降序列出n个整数集合中k个对象的所有和

def find_combinations(nums, k):
    results = []
    
    def backtrack(combination, start, count):
        if count == k:
            results.append(combination)
            return
        
        for i in range(start, len(nums)):
            num = nums[i]
            backtrack(combination + num, i + 1, count + 1)
    
    nums.sort(reverse=True)  # 按降序排列整数集合
    backtrack(0, 0, 0)
    
    return results

n = [1, 2, 3, 4, 5]
k = 3
combinations = find_combinations(n, k)
print(combinations)