力扣 862. 和至少为k的最短子数组

解法：前缀和+单调双端队列

def shortestSubarray(nums, k):
    # 前缀和+单调双端队列
    sums = [0]
    for num in nums:
        sums.append(num + sums[-1])
    
    queue, ret = deque(), float("inf")
    for i in range(len(sums)):
        while queue and queue[-1][1] >= sums[i]:
            queue.pop()
        
        while queue and sums[i] - queue[0][1] >= k:
            ret = min(ret, i - queue.popleft()[0])
        
        queue.append((i, sums[i]))
    
    return ret if ret != float("inf") else -1