Leetcode 209. Minimum Size Subarray Sum

Given an array of n positive integers and a positive integer s, find the minimal length of a contiguous subarray of which the sum ≥ s. If there isn't one, return 0 instead.

Example:

Input: s = 7, nums = [2,3,1,2,4,3] Output: 2 Explanation: the subarray [4,3] has the minimal length under the problem constraint.

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).

Difficulty:Medium

Category:

Solution

Time complexity: O(n), Space complexity: O(1)

class Solution {
 public:
  int minSubArrayLen(int s, vector<int>& nums) {
    int n = nums.size(), left = 0, right = 0, ans = INT_MAX;
    int sum = 0;
    for (right = 0; right < n; ++right) {
      sum += nums[right];
      while (sum >= s) {
        ans = min(ans, right - left + 1);
        sum -= nums[left++];
      }
    }
    return ans == INT_MAX ? 0 : ans;
  }
};

Relative problem

By guozetang            Updated: 2020-09-19 13:02:30

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