2023-07-06 Daily Challenge

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In: DailyChallenge
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Today I have done leetcode's July LeetCoding Challenge with cpp.

July LeetCoding Challenge 6

Description

Minimum Size Subarray Sum

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 <= 109
  • 1 <= nums.length <= 105
  • 1 <= 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)).

Solution

auto speedup = [](){
  cin.tie(nullptr);
  cout.tie(nullptr);
  ios::sync_with_stdio(false);
  return 0;
}();
class Solution {
public:
  int minSubArrayLen(int target, vector<int>& nums) {
    int sum = 0;
    int start = 0;
    int answer = INT_MAX;
    for(int i = 0; i < nums.size(); ++i) {
      sum += nums[i];
      while(sum >= target) {
        answer = min(answer, i - start + 1);
        sum -= nums[start];
        start += 1;
      }
    }
    return answer == INT_MAX ? 0 : answer;
  }
};

// Accepted
// 20/20 cases passed (28 ms)
// Your runtime beats 99.24 % of cpp submissions
// Your memory usage beats 71.68 % of cpp submissions (28.1 MB)
Algorithm