Shortest Subarray with Sum at Least K
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# LeetCode #862: Shortest Subarray with Sum at Least K (C/C++).

hard

source: https://leetcode.com/problems/shortest-subarray-with-sum-at-least-k/
C/C++ Solution to LeetCode problem 862. Shortest Subarray with Sum at Least K.

## Problem

Given an integer array nums and an integer k, return the length of the shortest non-empty subarray of nums with a sum of at least k. If there is no such subarray, return -1.

A subarray is a contiguous part of an array.

## Examples

### Example 1:

Input: nums = [1], k = 1
Output: 1

### Example 2:

Input: nums = [1,2], k = 4
Output: -1

### Example 3:

Input: nums = [2,-1,2], k = 3
Output: 3

## Constraints

• 1 <= nums.length <= 105
• -105 <= nums[i] <= 105
• 1 <= k <= 109

## Solution

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 class Solution { public: int shortestSubarray(vector<int>& nums, int k) { deque<int> dq; vector<long long> pSum(nums.size(), 0); long long sum = 0; int minSize = nums.size() + 1; for(int i=0; i<nums.size(); i+=1) { sum += nums[i]; pSum[i] = sum; if (pSum[i] >= k) minSize = min(minSize, i + 1); while(!dq.empty() && pSum[i] - pSum[dq.front()] >= k) { minSize = min(minSize, i - dq.front()); dq.pop_front(); } while(!dq.empty() && pSum[dq.back()] >= pSum[i]) dq.pop_back(); dq.push_back(i); } return minSize == nums.size() + 1 ? -1 : minSize; } };