Leetcode172: Minimum Size Subarray Sum

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

For example, given the array

[2,3,1,2,4,3]

and

s
= 7

,

the subarray

[4,3]

has the minimal length under the problem constraint.

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