leetcode-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.

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More practice:

If you have figured out the O(n) solution, try coding another solution of which the time complexity isO(n log n).

class Solution {public:    int minSubArrayLen(int s, vector<int>& nums) {        if(s<=0||nums.empty())            return 0;        int begin=0,end=0;        int size=nums.size();        int sum=0;        int minLen=INT_MAX;        while(end<size){            sum+=nums[end];            while(sum>=s){                if(end-begin+1<minLen)                    minLen=end-begin+1;                sum-=nums[begin];                ++begin;            }            ++end;            }        return minLen==INT_MAX?0:minLen;    }};