209. Minimum Size Subarray Sum
Đề Bài
Given an array of positive integers nums and a positive integer target, return the minimal length of a subarray whose sum is greater than or equal to target. If there is no such subarray, return 0 instead.
Example 1:
Input: target = 7, nums = [2,3,1,2,4,3] Output: 2 Explanation: The subarray [4,3] has the minimal length under the problem constraint.
Example 2:
Input: target = 4, nums = [1,4,4] Output: 1
Example 3:
Input: target = 11, nums = [1,1,1,1,1,1,1,1] Output: 0
Constraints:
1 <= target <= 1091 <= nums.length <= 1051 <= nums[i] <= 104
Follow up: If you have figured out the
O(n) solution, try coding another solution of which the time complexity is O(n log(n)).
Thuật Toán & Kỹ Thuật
⏱️ Thời gian
O(log n)
💾 Không gian
O(n)
Lời Giải
Python
0209-minimum-size-subarray-sum.py
class Solution:
def minSubArrayLen(self, target: int, nums: List[int]) -> int:
n = len(nums)
pref = [0 for _ in range(n + 1)]
for i in range(n):
pref[i + 1] = pref[i] + nums[i]
if pref[n] < target:
return 0
res = inf
i = n
while i >= 0 and pref[i] >= target:
j = bisect_right(pref, pref[i] - target)
res = min(res, i - j + 1)
i -= 1
return res