# Minimum Size Subarray Sum Problem

## Description

LeetCode Problem 209.

Given an array of positive integers nums and a positive integer target, return the minimal length of a contiguous subarray [nums_l, nums_l+1, …, nums_r-1, nums_r] of which the sum is greater than or equal to target. If there is no such subarray, return 0 instead.

Example 1:

``````1
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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:

``````1
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Input: target = 4, nums = [1,4,4]
Output: 1
``````

Example 3:

``````1
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Input: target = 11, nums = [1,1,1,1,1,1,1,1]
Output: 0
``````

Constraints:

• 1 <= target <= 10^9
• 1 <= nums.length <= 10^5
• 1 <= nums[i] <= 10^5

## Sample C++ Code

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class Solution {
public:
int minSubArrayLen(int s, vector<int>& nums) {
if (nums.size() == 0)
return 0;
int minlen = INT_MAX;
int sum = 0;
int left = 0;
for (int i = 0; i < nums.size(); i ++) {
sum += nums[i];
while (sum >= s) {
if (sum - nums[left] >= s) {
sum -= nums[left];
left ++;
}
else {
break;
}
}
if (sum >= s)
minlen = min(minlen, i - left + 1);
}
if (minlen == INT_MAX)
return 0;
else
return minlen;
}
};
``````