Minimum Size Subarray Sum

Desicription

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:

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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).

Solution

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